I Have Reddish Brown Spots That Cover My Thighs And

I have reddish brown spots that cover my thighs and butt. It also has started coming up my back and some are on my stomach. They don't go away and are under the skin. My legs also broke out in a rash on my outer thigh today. I have seen a dermatologist and they biopsied some of the spots. They said it was an allergic reaction to medicine. I don't take any medications.