Suggest Treatment For A Pimple Like Bump On The Penis That Reoccurred After Popping It

Hi. A month ago I got a small pimple on my penis so I popped it. A couple weeks later I showed up again but much bigger. The circumference is probably about the same as a pea. So I just ignored it and thought it would probably go away but today little dark spots appeared on it and I m a little concerned. What is it and is there anything I can do about It? Should I worry?