J.T.
many many possibilites, could be appendix, could be gallbladder, could be constipation, could be gas, could be..... if the pain is severe, go to a physician asap, they will prob do some bloodwork and an u/s to rule out anything serious. hope you are feeling better soon :)
additionally, are you/could you be pregnant? also could be symptoms of a rupturing ectopic pregnancy or even an ovarian cyst...