Cats, ragweed (which has transplanted itself to if I eat cantaloupe, watermelon, and banana now, as apparently there are some proteins that resemble ragweed on those; nice job, immune system, you just defeated my favorite food when I was in elementary and middle school, cantaloupe
), probably some sort of unknown indoor allergy as if I don't take allergy medication year round my nose tends to be a bit confused, mosquito bites (though not at all to the extent that people are allergic to bee stings; it's just that I can terrify people with the extremity of mosquito bites if I make any sort of physical contact with the bite location after I'm bitten).
I once had someone tell me it would make sense that I'd have a lot of allergies. I wasn't at all sure how to take that comment.