What Do Itchy Bubble Type Rashes On Legs And Hands Indicate?

Since the superbowl first week of this month my boyfriend, broke out with severe hives...target like...around legs at first, then hands and even had these bubble type lesions in his mouth. At worst point it spread with heat to touch to head to feet and mouth. After course of prednisone, antibiotics etc it calmed but has yet to go away. His doctor seems to think its arthritis related? We were told in the Emergency room when his tongue swole with these lesions (allergic reaction). Its been too long a course for a allergic reaction and his hands have these knots now...same bubble type rash and very itchy and spreading up his arms. Still has places inner thighs that swelled up and upon going down are bruise like...blue/ like damaged places. All the places he had the spots did it. I am worried! Any of this sound familiar or close to anything u have heard of?