Hi I'm 15 and about 2 or 3 weeks ago I found two singular bumps on the shaft of my penis and I don't know what they are, I've kind of been doing research and I think they might be sebacious systs or something but I'm not sure there small white, and for a while one of them was very red and they won't go away. Also 3 or 4 months ago I found a pimple around the base of my shaft and it soon turned black then it looked like there was yellow puss in it, and one day it popped and yellow puss came out. What do you think it was?

Sounds like an ingrown hair to me...

For the other bumps, if you are really worried make a visit to your doctor.