I'm 20 years old, I don't have an STD, and haven't had sex since I was 18. I've always used protection. When I get an erection, there is a snake-like bump under the skin that develops. Sometimes it's bigger than other times, and will get bigger after masturbation. I first noticed this about a year ago, but I'm starting to date again, and I'm very self conscious of this on my penis. Is this dangerous? Should I see my doctor? Thanks!