Help!!! Itchy rash.. maybe hives.

Khyna
Okay ladys i have this rash all over my body exsepted my fash. I never changed anything in my diet or in house hold products due to being alleric to alot, but point being i hurt from itching alot. I am 12 weeks pregnant today and my bfs mom is a rn and told me to take benadryl but im scaref to she said i would realy need to check with a dr. Would anybody on her know if it is safe to take?