hi there.. i was experiencing a similar problem a few months back.. in my case it was ameobiasis..other options can be either gastric pain or appendicitis.. i guess if it persists consult a doc.. take care.. good luck.
how has your bowel movements been? you could be constipated or maybe suffering a ibs attack
I've seen this happen when menses gets trapped behind scar tissue in the uterus, but I don't know that this is the case for you. Please see an OBGYN for a thorough examination.
Good luck and keep us posted.