If the benedryl takes care of it, it would be hives or an allergic reaction of some sort. If it does not or red spots appear go to the local outpatient to have a doctor look at it. I developed shingles and they presented similarly (mine were on my left side though); they hurt and are contagious if you don't get them right away.

Glad to hear you're feeling better mentally

Good luck

Cheers,

Brian.