hives

anybody got Hives during their pregnancy? I'm 28 weeks + and suddenly got hives 2 days ago. at first I thought it was a new food allergy but it has been 2 days and still not better! it's driving me insane! any tips/advice? I have been to the doctors and given steroid cream and anti-histamines but neither is working. my hives might appear to subside only to come back when I'm sleeping.