Ive had heavy clotting periods, Ive had really thick
brown discharge at the begining and end
before, Ive had it so dark it almost looked black. And its all just variations in how your hormones influence your period. And with a change in your birth control schedule, that could be totally normal. However, if you are still concerned about it get it checked out. There's no amount of advise from random people that will make you relax if you aren't convinced. Hope that helps.