What happens when Andy and I eat things we shouldn't?

This is a rash on Andy's arm that he has been scratching at and I didn't catch right away.
These hives are just starting on his upper leg. They are super itchy.
This is a fungal rash from dairy products on my leg. The round appearance is a clue to it being fungal.
These are some itchy hives on my hand from eating gluten.

I am not really sure what is causing Andy's latest round of hives, but we have been fighting them for about 3 weeks now. I treat them with prescription ointment and they go away pretty quickly and the next morning a new crop pops up somewhere else. We are think we may have figured it out and that it is Bananas - but we are not really sure yet.