Ok so I had protected sex a few months ago with my girlfriend and a few days after I noticed this small bump on the shaft of my penis. It's small, hard, and doesn't hurt. I didn't think much of it and continued my sexual relationship with my girlfriend. A few months after that, the bump kinda liked swelled up and started hurting, and then it popped but all that came out was blood. The bump went away but then a few days later it came back. Now it's at the point where I think it's about to pop again. I've done my own research and I'm fairly certain it's not an std. I just want to know what exactly it is and how, if I can, to get rid of it