Which specialist should I see?

Severe hives for going on 5 weeks. Missed 2 periods (not pregnant). Already seen a dermatologist who put me on a 9 day course of Prednisone - didn't really help. Also on benedryl and zyrtec. I left a message for that dermatologist asking what my next step should be, but who knows what he'll say. He did put me on Erythromicine because a history of strep test, although "inconclusive" did suggest I may have had untreated strep in the past. And, my throat was hurting (I think it was just hives in my throat). I know to get allergy tested I have to be off all meds for 5 days - even benedryl - not sure I can do that. Should I see an Endocrinologist since I've missed a couple periods and maybe it's hormone or thyroid related? Or should an allergist be my next step? Any suggestions?