About a month ago I noticed that the skin on my penile shaft had become darker with small brownish spots that also some on my penis head. They dont itch, irritate, or burn and have not gone away. I have never had bumps or anything. I've been tested for HIV Sphyllis Claymedia and Gonnerea all coming back negative. Could this be penile cancer? An infection due to some untreated STD? I know theres not much you can tell me online but I'm awaiting a doctors appointment and scaring myself senseless googling symptoms. Please help