Columbine, thank you for the info! June was an extremely rainy month around here, and mold counts have been high or very high all summer, so perhaps that's the culprit.

I'm hoping it's not food allergies. Regulating his diet will be tough because (once his appetite returns to normal) it won't be easy to keep him out of the other cats' food.

I'll look into the chlorpheniramine and the emu oil. Thanks again!