I had unprotected sex with a girl I do not know anything about. This was during Christmas time. Last week after working out at the gym, I got a rash that lasted about 10ish minutes and then went away. Then again this week after coming back from the gym, I got the same exact rash, and again it went away in about 5 minutes. It appeared on my thighs, shins, and arms and tops of my hands.