Does it happen after you ejaculate? I sometimes suffer from a similar pain in the abdomen after masturbation..it sometimes gets unbearable...it took me a good 10-12 yrs(since i got sexually active) to understand exactly why it was happening.. I found out tht it only happens if i urinate before masturbating..usually within one hour before masturbating... If i dont urinate before masturbating, or say the gap between the last time i went to pee and masturbation is more than 1-1 1/2 hours, then it doesnt happen.. Strange it is..i dont know why it happens or why the 1 hour phenomenon.But i've learned to control my urges and i make sure tht i dont masturbate within an hour of peeing... Since then, i've not suffered from tht pain in the abdomen at all..
I dont understand how it works or whether it'll work for you or not..but, for me it does! No harm in trying..aint it?