I've Been Having Troubles With My Menstrual Cycle, I'm Experiencing

I've been having troubles with my menstrual cycle, I'm experiencing black and brown blood from the beginning and it has been very watery which is different than the usual period. I'm on the contraceptive pill (Lucette) and also ciclosporin for my immune system I have seen it's a rare side effect to have menstrual imbalance but am worried what these effects mean.
I am sexually active but however am on the contraceptive pill.