I Think I May Be Having A Reaction To Benadryl.

I think I may be having a reaction to Benadryl. I have a severe rash and unsure of the cause - PCP is unsure of the cause unless a reaction to sulfa drug - I took a shot of decatron. It looked like the rash had brgun to clear up however,I was still have severe itching associated with Very painful rash. So I took another Benadryl and not the rash is full blown and very painful . I can almost tell when another. Spot is popping up. I am just curious if the Benadryl could have a reverse affect on me.