have you been to the doc at all? and when are you supposed to have your period? it could be anything, are you on any meds at the moment?
It could be a lot of things - cramps, lower intestines maybe... I get pains from cramps before my period, sometimes at random times, and then I also have some digestive issues & I get cramping in my lower intestines -- almost feels like period cramps, but it's not.... You will definitley want to visit a DR to make sure it's nothing serious, especially if it continues.
good luck
Unfortunatly, I don't have an answer but, there are several women that suffer from chronic pelvic pain and lower abdominal pain. See your doctor asap!