Allergic to work?

I don't know if this is the right place, just trying to be generalized as possible.

So I think I'm allergic to work. Not trying to sound funny but for the past couple of days, on the days that I work I'm starting to break out in these nasty hives. They only appear on exposed parts of my skin, they seem to respond to Benadryl nicely but as you guys know: Drowsy City. (I work night shift :/)

Any advice?
We suggest that you contact your medical provider. There can be many allergens in any work environment. However, per our terms of service, we can't provide medical advice.