I agree with Artchic. You are the best advocate for your body. I would ask the doctor for clear documentation on what it is (they can provide print outs and link with information that elaborates on your "diagnosis"). If they are not willing to do that, I would easily suggest seeking a second opinion, visiting an urgent/doctors/med care (not the ER). Or, perhaps even asking them to take a culture to verify its not an STD of some sorts. If its not, then yay! you could then go to a dermatologist to address the discomfort they are presenting you (aesthetically) and possibly get better insight of causes and solutions on how to eliminate them.