I am 19 had unportected sex a couple of days ago, the only time I have ever had sex, on Thursday or Friday. By saturday, I noticed only the head of my penis was spotted with several red spots that seemed to be flat. They seemed to stay the same. By today, Monday, however, the bumps nearest my urethral opening seem more inflamed and perhaps bigger. It itches occassionally but doesn't hurt. Could this be an STD, given the fact that it appeared so quickly (1-3 days after sex)? Or could this be a yeast infection? Please help me.