help. period\ birth control

So I just got birth control and I started my period 3 sundays ago. I had my period for 9 days then it stopped thought I was done then the next day it came back then the day after that it stopped and now it keeps repeating. Like it won't be there one day but it will come back the next. It has been on one day then the next day not there for 2 weeks so it's like a repeating thing. Help! Is there something wrong or???