Acne. Please help me.

I have really sensitive skin so I've never done much with it. Luckily I never had major problems with acne so I didn't exactly need to. Usually I just rubbed and rinsed my face in the shower using only water. It seemed to be happiest with that.

But now that I'm pregnant, my skin has gone completely crazy. I'm breaking out on my back, on my chin, forehead and cheeks, even my scalp has pimples. Some of them really hurt. What can I use that will help without breaking me into a horrible rash?