I am 32 and the other day I noticed a small lump on the underside of my penis, at first I thought it was just a pimple. So I squeezed it, I felt something pop, and figured it would go away. Much to my surprise it didn't and now has become a large knot and is very noticeable at any point, whether I have an erection or not. I'm getting a bit nervous. Is this a cyst or something worse?