I just recently got over a stomach virus on Wednesday. I started getting menstrual like symptoms on Thursday. I have had light to heavy bleeding Thursday through Monday. It is Tuesday and the bleeding is lightening up a lot. I have also had very uncomfortable cramps along with the bleeding. I am on a low dosage birth control pill and last month my dog chewed up my pack and most of the pills were lost. I took less than half of the pack. I started a new pack this month. I am not scheduled to get my next period until two weeks from now. What could be causing the bleeding and cramps?