Hey, I have the exact same thing in the left side of my penis about an inch up and it seems to be a lump in the foreskin or something. It is only painful when I press on it, it is red and kind of had, and looks like it stops where one of the hairs comes out, so it could be associated with that. I just appeared the other day and could be from masturbating, I'm unsure. There is no way that mine could be an STD, and I've seen the same thing on some other forums and there doesn't seem to be any indication of it being an STD. It kind of fits the description of cancer, but it seems much to sudden to be that. Please post any answers you come up with here, if mine doesn't go away in a couple of days I will go see my doctor, unless it seems to be getting better.