Is it weird?

I have been on birth control for seven years... Never had an issue. The past three years I haven't had a menstrual cycle worth noting, until last week it was the WORST period I had since being on birth control, extremely bad cramps/back pain/lack of appetite. And since that period ended I have been soooo moody, my appetite is all over the place, and a sour feeling in my stomach. Is the pill no longer doing it's job, maybe just a stomach bug? (Making a doctors appointment if another painful cycle occurs) also a friend mentioned endometriosis as a reason for all the pain...