Hi! I have a son who is allergic to milk and egg.
His first reaction was at 4 weeks old. I was going to be going back to work and wanted to get him used to an occasional bottle of formula in case I wasn't able to pump enough milk for the babysitter. It was very scary because his reaction was projectile vomiting and screaming. We immediately took him to the hospital. They suggested we keep him on soy formula when using formula and that seemed to work fine.
Now I have to tell ya, I never needed to keep egg or milk out of my diet while breastfeeding, so I am not sure if that is necessary. I think only an allergist can tell you for sure. My son did not get an official diagnosis or visit with an allergist until he was about a year old and no longer breastfeeding, so I never talked to the doc about that. But I can tell you that he never had a reaction based on my diet. (But perhaps that varies)
He will be two in a few weeks and was recently tested again. He is still allergic to egg and milk, BUT the allergy levels have decreased, so that is definitely reason to believe that he may grow out of it. Yippee!!
As for the allergy, if you haven't already, get a test done so that you know for sure. The testing isn't that bad. My son went through ALL of them because his first round of tests had him allergic to almost everything, so they had to do more tests to be certain.
About grocery shopping... you will have to check labels of EVERYTHING. You will be suprised at how many things contain milk. He's getting to the age where he can eat just about anything. Every time you buy anything, you have to look at labels because they can change. Or the same brand may vary based on one tiny detail, like shape or flavor. I was suprised when I started to see milk listed in the ingredients for BREAD and animal crackers!
There is always a chance that there will be mistakes along the way. That's why you need a diagnosis and perhaps an epi-pen. (We have three but so far haven't had to use it) because a true allergy really is life threatening. And it is important to realize that. When the enzymes in the body go on the attack, they can sometimes cause the throat to swell, cutting off air supply. So you NEED to know for sure what you are dealing with so you can act accordingly.
It is important too, to make up for any possible deficiencies that may arise from not having milk. Soy, rice, or almond milk are all great alternatives. But also be sure to read the lables. I have learned that there is milk in many many soy products. SO just because something claims to be soy yogurt or something, it doesn't mean it's also dairy-free.
We were told to give our son lots of peanut butter to make up for the fats and proteins he's not getting from milk and egg. Luckily he LOVES peanut butter. We also give him a Calcium supplement and vitamins. (He's able to eat the gummy types).
Also, have him tested for egg allergies before getting any flu shots for him. That's actually how we learned of his egg allergy. I was going to get him one and the nurse asked if he had egg allergies. I suspected he might, just because of the milk reactions. Flu shots are somehow made in some sort of egg incubator. THANK GOD for that nurse. If she hadn't told me that, I would not have known. As it turned out, his egg allergy was worse than his milk allergy. The egg allergy was so high, it was off the charts! That shot would have certainly landed him in the hospital, if not worse.
When you go to restaurants, if he is allergic, you have to ask what everything is cooked with, in, or near. If there is no milk ingredients, you have to know that other things with milk ingredients aren't cooked in the same fryer, pan, griddle, etc. And always bring along something he CAN eat, just in case. SO I usually pack a banana, or apple sause, or a PB&J sandwich.
Hope some of this was helpful.