Kind of freaking out.....

I am on birth control and my period isn't due for another 3 or 4 ish days.. But I have been bleeding like I'm on my period for the past week and a half. It's really starting to scare me because there is no sign of it easing up and if it doesn't I will have bled for 3 weeks straight when my ACTUAL period gets here. Has this happened to anyone else??