My son has had a small rash on the inner parts of his bottom cheeks (not in crack area) and I thought it was just heat rash. Here, 3 months later he shows it to me again and it's bigger on both sides, scabby and has fluid coming from it. He says it's itchy too. What in the world could it be? He has been wearing boxers, I have not changed detergent, and he says nothing rubs there.