He doesn't seem to have a problem with gluten, but 2 of my other children have the "chicken skin" on the backs of their arms that is a symptom of gluten allergy. But getting them to stop eating gluten? Prolly not gonna happen.
That's a ton of allergies!!! My daughter (now 23) has a shellfish allergy to the point where she needs to carry an epi pen. She has always had problems with dairy and soy, so she drinks almond milk. I had a milk, wheat and nightshade allergy as a child but grew out of them, she was not as lucky. We are also allergic to cats (and have a ton), and I'm really allergic to horses (but have an equine science concentration in my animal science degree and rode competitively for a while).
Your son really lucked out by not having problems with poison ivy!!