Night sweats and welts?

SL
Im 4wks pp and have been sweating at night- which I've read is typical after pregnacy. However, I noticed in getting itchy hives/welts when I'm overheated. They are gone by morning. Sometimes I have to take a benedryl to stop the itching. I haven't changed anything like detergent etc so it's not an allergy like that. Anyone else have this? Am thinking my hormones r out if whack at the moment and this may be the reason.