I am on birth control and have over a week worth of pills left before I am due for my period but for some reason I seem to be getting my period now and have had a slight pain in my lower abdomen (the same pain as when I have to poop) for most of the day. I ha vent missed any pills this month so I don't know why my period is starting now. Could this be some kind of internal bleeding? I am getting very worried!

If you are that concerned then a trip to your own medical practitioner or hospital would be in order.
We cannot make any kind of diagnoses over the internet.