Period after ending BC

Kasey
I finished my last pack of BC on June 25th. I know my hormones are going to be all out of whack because of ending BC. AF is not due for 5 more days, but today I had some super dark red/brown discharge. A lot of it. I'm assuming this is just my period, but it have been this dark.  Am I correct in this assumption? And why is it so flipping dark?