HI I have a small bump on the shaft of my penis, its tiny, dark around the edge and its got a red shiney surface, ive had a few before, and picked them off with my finger nails because i was so frustrated with them. In the process it showed a little blood, hurt quite a bit, but it seemed to heal well and left no scar and all was fine... But now theres another one back. Any idea what this is? Or if I should worry?