Help me! Please!

I'm 18 weeks pregnant and the last 3 weeks I've been having a skin rush that is unbearable!!!!! I saw a dermatologis who said it's a pregnancy thing and I will have it until I give birth. Its itching and I can't even sleep or put pants... I've tried aloe vera, one other cream that its ok to use when pregnant and a cream the doctor gave me but nothing helps!!!!! Please I'm I the only one? What can I use to be relieved? The rush started as a few bumps and then it formed into big spots all over my body... it's terrible..