What Causes Penis Pain After Masturbation?

i am 21 years old unmarried i used to mastervate from 5 or 6 years most time i noticed that i fell pain at my penis in 2nd time mastervation after 1st time mastervation the time duration between 1st and 2nd mastervation may be 7 or more hours still i fell pain now i want to know is is normal or abnormal