Hi,
It certainly sounds like a reaction to something in the bread. Probably the wheat - but what other ingredients were in there? Milk/soy reactions can be mainly GI related, where as other symptoms that are true allergies (not intolerances) can show with things like hives. Having such a quick reaction, especially with the hives, indicates it most likely was the new food that was introduced. If it was solely GI related then it might be questionable, does that make sense?
Just sitting doing DF and thinking about all of this and your comments here suddenly clicked in my brain! Where you say GI related do you mean where the foods are digested through to the bowel and react? That would make sense with the delayed reaction to milk and his symptoms being wind, thick/digested sick.
Yes, exactly what I was saying.
,,,and for sure get some benadryl or another antihistamine (check the ingredients to make sure it's safe). You should let everyone who is around him know that he is very allergic to wheat (at the least) and that no one should give him anything to eat unless it's a food that has been approved by you. There are always some good hearted people who think they have "safe" foods and give to him which may cause a reaction, very important to have benadryl or equivalent handy for them (and you). I would let them know what the symptoms are (i.e, if he breaks out in a rash/hives, swelling, and ESPECIALLY any wheezing/respiratory symptoms) - let them know immediately how much to give and who to call (I used to write it all out and give to my parents when they babysat).
Lastly - perhaps start thinking about a ped allergist visit. They can help determine if there are any other allergies and also help with a game plan for introducing solids.
(((HUGS))) - it can be a bit overwhelming in the beginning, but you'll find soon that it just becomes the normal way of life and you both adjust accordingly.