About 6 weeks ago I noticed a small red patch on my penis. It has grown very slightly since the time I noticed it. I don't seem to be suffering any std symptoms that I can find on the Internet. I'm not sure if it's a rash, "carpet burn" from sleeping nude or occasionally just my underwear. But I don't want to waste a trip to the doctor if it's nothing, which is the advice I expect to get. Any insight is appreciated.