9 weeks pregnant with really bad rash, What to do?

I'm about 9 weeks pregnant and I went swimming yesterday with my family at the lake. The water made me break out! I don't know why but it did. EVERYTHING I have tried doesn't work include Hydro-cortizone cream and exima medicine, Rash cream, Aloe Vera, aspirin((just for the hell of it!)) .... When it started I had just got out of the water and it started on my arms, shoulders, and neck. It's now on the inside of my thighs, My sensitive area, Under my breast, my arms, my under arms, and calf. It itches REALLY bad, it's red from itching it so much, I barely slept last night and there's a TON of bumps. They hurt REALLY bad from itching so much. Any suggestions? I go to my OB Friday but I cant live like this for that long....