Weird period... kind of worried?!!!!?

Ok so i had my period about 2 weeks ago, but after my period i had a little bit of BROWN spotting, and i thought that was pretty weird. Today i went to use the restroom and saw that it looked like i got my period again, but it wasnt red, it was DARK BROWN???! This has never happened to me, but i started taking birth control 2 weeks ago so that may have something to do with it. Thank you for your help!! And that dark brown heavy spotting is still going on. it has been going on throughout all of today.