Red Bump Shaft Penis

Patient: Hello my name is Max and about 2 weeks ago i noticed a little bump on the shaft of my penis…it had a white head at the top so i researched it and thought it was a pimple and would go away on its own. But i realized yesterday that it has now grown bigger about the size of my pinkie finger nail. The white part at the top has disappeared and it has turned red and it does hurt when i touch it. I would just like to know what i should do. Also i have never had sex, and i masturbate often. thank you for all your help. I am 16 years old.

Doctor: