What Causes Sharp Pain In Penis While On Erection?

Hi yes I'm 24, and have had some complications of getting erections for a few months now. I finally noticed, I have little dotted bruises on tip of penis and when ever any pressure is applied or have an erection from masturbation too long I feel a sharp pain and then dullness. What could be attributed too this? What could be some treatments? I'd like to get my mojo back.