Does Bc Tablet Cause Prolonged Menstruation?

Hi, I just started birth control a little over a week ago. I read the instructions on the package and it said I could start the pill within 24 hours that I start my period, so that's what I did. I started my period on a Friday night, the 13th, and took the pill the next morning when I woke up. It's now been over a week and a half (it's the 24th now) and I'm still on my period. I've been having horrible cramps this past week and a half and just feeling really fatigued. What's the deal? Is my period going to be like this every month now because of the pill?