I have been taking Sprintec birth control pills for four years and never had any problems with my menstrual cycle. This month, a week after my normal period started, I started bleeding again. After three days of this continuing, I went to my doctor and they think that changes in my body is making it so that my birth control pills aren't reacting well anymore. They switched me to a different brand and said to finish my original pack and then start the new brand. My question is, can the birth control pills really be making me bleed for 9 days straight, with abdominal pain, and if so how long before I stop bleeding? Also, if after I start the new pills and I continue bleeding, how long before I should go back to the doctor?