What Causes Purple Pimple Under Penis?

I have what appears to be a pimple on the underside of my penis. The first couple of days it was just a red, but this morning I woke up and it was purple. It hurt slightly when touched, but nothing extreme. This afternoon, I found it bleeding. It wasn t extreme bleeding, just consistent. I ve never had sex, so I know I couldn t have contracted an STI. I m just looking for someone to clarify whether or not it is just a pimple, and how to go about handling it. Thanks in advance for the help!