Rash on thighs? 20 weeks

Mackenzie • Baby boy born 9/6/18 & 1/18/21 💙💙

I had a slight rash on my belly that was itchy and red but not raised or painful like my thighs are now. My thighs are now painful to the touch and my stomach is almost cleared up. (My OB saw my stomach and dismissed it and said to take Benadryl). My thighs get worse every day and are spreading quickly. Has anyone experienced this? You can still slightly see my redness on my stomach.