Expert Q & A Answers About red spots penis

I have red spots on my penis after unprotected sex...what are they?

I’m a 31-year-old male who has been stupid and had unprotected sex. Now I have a few red spots on my penis and the skin seems to be rubbing off. When I touch the spots, it stings a little. Also, one side of my penis is slightly swollen. Can you please let me know what you think it is?