My doctor put me on birth control for my unbearable cramps and ovarian cysts so i don't get periods anymore but i have one right now.. why?

What kind?: If you are on birth control pills, and are taking the placebo week (one week out of four with most pills; one week out of 12 with seasonale/seasonique) you should have a period when you stop taking your active pills. Progestin only pills are a little different, though. You don't take inactive pills, just active ones. With those, you might not have regular periods, but have breakthrough bleeding.