Hey, I have a a red circle on my penis head, it's about 1 inch in diameter, it doesn't hurt or anything, it just turns more red when erect. I don't have STDs or such. But I do masturbate a lot. I've been looking for an answer, but doesn't seem to be getting me anywhere. One suggestion to me was that it's probably because I masturbate too much, and I cause the penis head to have a stretch mark or something.