to bleed or not to bleed

I've been taking mononessa birth control since October of 2016 and last month my doctor told me to skip my sugar pill and start a new pack once the time came. So here I am on the new pack, and I'm supposed to have my period right now. But I've just been having reddish/brown discharge for about 8 days now. What do I do? Should I be worried? How long will this last? SOS