I've got a mark of my penis, it looks flat, and red and gets a little wet. recently had unprotected sex with my new girlfriend who has told me repeatedly she gets tested and doesn't have anything, this is about 2 days after the unprotected sex. but I also masturbate and don't really clean up after myself before going to bed and am wondering if it is possibly just an infection? or I hope :( Its about the size of a pea