E.B.
My daughter has had multiple endoscopies, biopsies of stomach and several other organs, has swallowed a camera in a small pill that took photos of her entire digestive process, and once had to keep a tube through her nose down to her stomach for 24 hours. That was uncomfortable and weird.
But don't be worried or terrified. There are so many reasons for that feeling of something in her throat.
There is something called a globus sensation where there is no physical problem but a very real sensation of something in the throat. Treatments may include swallowing and speech therapy, antacids, or other fairly minimal approaches.
My daughter has lupus and has a dry esophagus (not a dry mouth - it was what was causing that feeling). She takes a medication three times a day that is a cholinergic that produces more mucus and relieves the feeling of blockages.
Also, you might consider getting your daughter to a good dentist. Sometimes there is a piece of food that's been stuck in a small hidden area, or a piece of baby tooth, that just is lodged there and can be felt. Tell the dentist what your daughter experiences and request that the dentist carefully examine the throat as thoroughly as possible for any obstructions. Make sure it's not just the hygienist, but the actual dentist who evaluates your daughter's mouth and throat.
Also, there are dry mouth rinses that may help - they're available in pharmacies over-the-counter. There are also sprays sold in health food stores for throat relief - they're not medicinal, they're just things like honey and other soothing things that people who talk a lot (professors giving lectures, for example) or people who sing use to keep their throats well lubricated and not irritated.
Your daughter might end up not having any problems at all. Perhaps she's consistently dehydrated, or chewing a lot of gum, or perhaps she's developed a habit of clenching her jaw in a particular way that causes discomfort. Make sure she's not eating things with artificial sweeteners - use raw local honey or maple syrup for sweetening things. Pay attention to what she eats and drinks. Maybe she's eating a lot of dry crackers or chips and not drinking enough fluids.
The doctors have ways of making the procedures seem less scary for a child, and your child might not have any problem with it at all. Please try to focus on using all the available tools to help your child feel better, and make yourself part of the team that's doing all they can to figure out what this sensation is. If you're terrified and dreading it, you can't be as helpful. Call on your inner strength, from whatever your source (God, meditation, exercise, rest, an enjoyable hobby, a dear friend) and know that you can handle this.