Pain in penis after a couple days of maximum masturbation?

Overuse syndrome. You would have to define "maximum" masturbation but if you have pain in your penis after a vigorous and prolonged and frequent masturbation session, then it is most likely overuse and due to trauma to the skin, urethra, underlying structures, nerves and will essentially be compared to a bruised penis. I would recommend you pay attention to this and consider your options to decrease the activity.
You were too rough. Try to be a littkle more gentle with yourself.