K.P.
My husband has had Crohn's disease for 13 years and the symptoms sound very similar. They couldn't diagnose him for the first three years, and finally diagnosed him during an emergency surgery to remove part of his small intestine. Since then he has had another brother get diagnosed with Crohn's and the rest of his family seem to suffer with irritable bowel syndrome, although it's not full-blown Crohn's yet. Diet, stress, and adequate rest are very, very, very important. Doctor's won't tell you much about diet, so you have to do a lot of research, keeping records, and trial and error yourselves.
With my husband, and the same has proven true with this brother (so these could be family things, but I believe they are all major irritants to anybody with as sensitive stomach and digestive tract), here's what's worked for them as far as diet goes...
Purified water: we've found that tap water makes my husband sick, no matter where it's from. We invested in a very high-quality water filter, and it's made a huge difference. It's important to drink a lot of good water to be healthy.
No caffeine: one little sip of Coke even and it causes pain. When he's very sick, even the caffeine in chocolate will irritate him. Caffeine is in some medications (Excedrin, for example, so be careful there).
No soda: even if it's caffeine-free, soda is hard on the stomach and will upset my husband.
Limited dairy: it's different for everyone, but my husband can't tolerate milk. He drinks soy milk (we think Soy Silk brand tastes the best). However, he can have cheese and other dairy products in moderation.
NO MSG: When you're reading for this on ingredient labels, its full name is monosodium glutimate. This is the number #1 irritant for my husband, and we've met several people with sensitive stomachs of some kind, and this is a trigger for pain for them as well. Monosodium glutimate is an additive that's primary purpose is to enhance flavor. However, it does this by overstimulating the glands in your mouth to overreact so the flavor tastes bigger than it really is. The problem is these glands are also throughout your body and so it can make your body overreact in sensitive areas and flare up. It's a terrible additive and is not healthy for anyone. It's primarily in things like broths (instead of using bouillion or canned broths--all of which contain MSG, we use bases--"Better than Bouillion" is a great brand, comes in all flavors, and tastes much better than bouillion anyway), gravies (make from scratch and you'll be okay), flavored potato chips (plain chips and Sun Chips are usually okay), ramen noodles (the flavoring packet is the culprit), salad dressings (especially most creamy dressings, we use LiteHouse brand, it's in the produce section), cheap chinese food (even if they say there's no MSG, it will make him sick), bacon, sausage, nearly all canned soups (except for Campbell's Healthy Request line), etc. The good news is you can usually find brands of all these things without MSG, you just have to carefully read labels. Be careful with eating out. Most restaurants, even nice ones, think they don't use MSG because they don't add it when they cook, but they don't realize it's already in some of their prepared foods--especially gravies, sauces or marinades, and salad dressings. Eating out in general usually makes my husband sick because it's just too hard to determine if those foods really have irritants in them.
Take care with preservatives: through trial and error we've found that some preservatives irritate my husband--primarily potassium sorbate and sorbic acid (not to be confused with ascorbic acid, which is vitamin C). Basically anything that ends in a "sorbate" irrites him. There might be others that do irritate him, but these are the ones we've pinpointed. Foods that contain these are soft flour tortillas and many yogurts, sour creams, and other dairy products. Again, these can easily be avoided and you can find other brands of the same item without this preservative.
Red meat: now, this doesn't always upset him. We do eat red meat. But we eat it in moderation and according to how sick he is at the time. Chicken usually doesn't upset him.
Artificial sugars: Another lady already explained this in great detail. We've never tried eliminating some fruits as she's suggested, but know that most fruits and especially fruit juices can upset my husband when he's very sick. Gum is a major culprit for irritating him, though. For some reason he can tolerate the "Orbitz" brand of gum, but I'd be careful!
Vegetables are okay!: Sometimes the only thing the doctors will tell you is to avoid ruffage, such as very fibrous vegetables and foods; however, and it may be different for everyone, we've found that vegetables don't upset my husband. If you're worried about it, I would just make sure they're well cooked. Some vegetables like broccoli are gas-producing, so that may hurt an already injured digestive tract. Anyway, just use your common sense here.
Take care with sugar: we've found that it's just too hard to completely eliminate sugar in my husband's diet. Remember that stress is a HUGE trigger for flare-ups. And it was just too stressful for my husband to give up sugar completely. I'm sure he'd be much better off if he did, but he'd rather handle sugar on his own terms and have the control over it. So he eats sugar in moderation. Sometimes when he feels himself getting sick, he'll self-discipline himself to cutting majorly back on sugar or completely eliminating it for several days to a few weeks. It does help the less sugar he eats.
Probiotics are great: It would be good for your daughter to supplement with a probiotic, such as asidopholus or lactobaccillus (I don't know if I'm spelling these right!). Anyway, these are the friendly bacteria that promote a healthy flora in your digestive tract. Make sure you are using a high quality brand. We like Culturelle (can be found in most pharmacies, Wal-Mart, etc.) Your doctor might be able to recommend some too. If you're only going to do one supplement, a probiotic would be the one to do.
A word of caution with "natural remedies." I think there is a lot to be gained and learned from using or researching natural remedies, but it can be VERY, VERY confusing, expensive, and extremely stressful when doing so because they all have 10,000 reasons why theirs is the only remedy that works, yet each remedy or natural treatment plan seems to completely contradict each other. We have personally spent thousands of dollars trying various methods. We probably learned one or two things from each method that in the end really helped and could be implemented realistically in our lives. I wouldn't discourage you from exploring the alternative route, but I will tell you to use your common sense and your gut intuition when you consider if you want to try these things. Your daughter, young as she is, has to be willing to try these things too, or they will just cause her more stress and that equals more pain in the end. All the do's and don'ts that I mentioned above that we do may seem overwhelming at first to you, but the nice thing is, for most of them, you can eat many of the same things, you just have to buy a different brand, so in the end the resulting diet doesn't feel too extreme for the sick person. People with Crohn's or other digestive disorders are usually underweight anyway, and some of these extreme natural diets only cause them to lose more weight, energy, and strength. So again, use your common sense!
It would also be wise for your daughter to eliminate as much stress in her life as possible. You need to stay positive for her and she needs to not feel forced or pressured into anything in life. Very ill people tend to get quite depressed too, so perhaps some professional counseling might help her get a better hold of her stress and anxiety and outlook on life. The more positive she is, the less sick she will be...because, again, stress is a MAJOR culprit for digestive disorders.
Good luck! Digestive problems are incredibly frustrating, but they can be helped. Hang in there!