Black/Purple bump on shaft

[Skyland]

I just recently turned 18 and got involved with a friend I've known a little over a year now, and only a few months ago did we actually have sex. We had sex on a number of occasions, and I never noticed anything wrong, but a few weeks ago, I noticed this bump on the shaft of my penis a couple inches below the head. Its only one, Pea-sized, bump and its a black, kinda purple, color. It doesn't itch, sting, burn, or anything, but it certainly worries me. I know my friend has been involved with a large number of other partners, so I'm wondering if she picked something up, and now I have it. I made sure to check for more, and fortunately didn't find any others. Please tell me if these are symptoms of something more serious, and how to treat it. I really don't want to start off my sexual life with an STD and possibly pass it on to any other partners I may come across.

Thanks,
Mark.

[gracefromHHP]

Still it's a good time to talk to your friend about std's and testing. odds are neither of you are getting proper testing done so do it while it's on your mind so you don't wonder when you get things like this.

grace

[Skyland]

I think I may have found a probable explination for this bump. As I recall, and I guess I shouldn't be afraid to admit either, I remember pinching my penis in my zipper when I was pulling my pants on. I was reading a few articles online and I realized that it could just be a sore spot where the skin was pinched. I'll make another post if it remains, but should this theory be the case, then I guess I got worked up for nothing.