What Is Sore Bump On Bottom Of Penis?

A few days ago I noticed a pea sized bump on the bottom of my penis shaft. Was a little tender. I shave so I thought it might be an ingrown hair. The lump was fairly firm to start. The next day it was a little smaller or at least less tender. But then I masturbated (which I guess I shouldn't have) and it seemed to make the bump a little larger. The lump under the skin seems to have spread to the sides a little. So instead of round its more oval now like it spread around the curve of my penis shaft. Its less firm than it originally was, like squishy but not pure fluid. And its more sore.Not sure what to do I don't have medical insurance and I am not sure which doctor I should just randomly go to.