I have a dark black patch around 3 to 4 mm on my penis head under the skin. It is flat and does not irritate me or doesn't pain. But it looks bad though. I m worried whether it is any diseases or infection. It is completely flat as if it is underneath the skin. I don't remember from when it is there but as long as I remember it is there from past 5 to 6 yrs I guess. Kindly help. If some expert contacts me personally I can post a picture too. PLZ HELP