I have a rash that has appeared on my scrotum/penis area that I noticed a week ago. It formed blisters and was painful at first but is now very itchy. I was concerned so I went to the clinic to be tested for STD s including herpes but the results were negative. The itching is getting worse and the doctor gave me antibiotics but it doesn t seem to have any effect The blisters are still there . Any idea of what it might be?