I seem to have a penis rash on the head of my penis.. there is red spots on my penis head but no burning sensation. I went swimming in saltwater today for about 5 hours and it was pretty hot. Also sat around in the sand. When i got home i showered and my penis was fine. I took a 3 hour nap and woke up with a rash. Also could this have anything to do with a weak immune system? I got like 4 hours of sleep that night.