I Went Swimming At 7:30 Am Today For About An

I went swimming at 7:30 am today for about an hour, and while I was changing, I noticed some small red bumps near the head of my penis and on the skin of the penis. I usually wear underwear and swim trunks when I swim, but today I didn't. I'm a 16 yr old virgin. Is this the chlorine? My swim trunks? Thank you.