Left testicular pain?

Hi, i dont know what the cause of this is but im having left testicular pain. Like i said i dont know why but i have a idea that its because i've been hitting it during masturbation, I have been feeling since i've started masturbation and i masturbate with my left hand and I think i might have been hitting it. im not to concerned but i read its normal for most men to feel this pain during some point. but i want to research more before i make a big case out of this so some help would be nice thanks.