Definitely have a Dr look at it. There are some small sized lumps the feel sharp or multi-sided that are normal. There are some that can get as big as a sweeteam pea that are normal. Then both categories have things that are not normal. Luckily, penile cancer is seldom found inside the shaft; it is usually on it. Monitor it every other week, and if it grows or moves, go to the Dr right away. If it does not grow or cause problems, just wait until your next Dr visit.