Hello, I Have A Red Spot On The Rim Of

Hello,

I have a red spot on the rim of my penis. It's red, flat, and not particularly painful. I noticed it about 1 week ago while madterbating. I do not think it's an STD, but am not sure. I was told that I had a yeast infection before, but that was on the shaft... this time the spots are on the corona.

I am sexual active and have recieved unprotected oral sex from multiple women over the past year.