Every now and then I get these little red dots on my penis near just below the head of my penis. I only get one at a time and they look kind of like a white head and if I pop them they just look like a tiny red dot that doesnt bleed or scab over. After about two weeks or so the thing is gone and there is no sign of it at all. These dots only seem to come about after I masturbate for an extended period of time. Usually after an hour or more of masturbating one of these dots will show up. Now is this herpes or some sort of STD or is it just a side effect of prolonged masturbation?