After masturbation i will feel a pain like if i pulled a hamstring / groin. why?

Pain-Masturbating?: Hi vigorous masturbation can lead to muscle strain and trauma that can be experienced as muscle strain or pain. I would also worry about trauma to the tubing inside of the scrotum. But, rest is often warranted. This would mean a few days without masturbation. Depending on the intensity of the pain adding an anti-inflammatory is also advised.