using any new products in the house that he could be allergic to? New furniture polish, carpet cleaner/refresher, kitchen cleaner etc.. Might try a new filter in the AC unit that stops allergens and stuff, but they are usually a few dollars more than a standard filter.. New body lotion, hair mousse, clothes soap, dryer sheets (extremely bad for everyone) or any other new products for anything that could be the culprit? New cat food? New gator food? My wife will sneeze when drinking wine - has he been hitting the sauce lately?
Friendship is like peeing your pants.. Everybody can see it, but only you can feel the warmth..