Brown discharge when period is due?

Ok so I have been EXTREMELY stressed out lately. And this is only my second month of ortho tri cyclen lo. My periods are generally really heavy only I don't know what's going on. I started noticing a brown discharge Tuesday night and I thought it was the start of my period. Well since I started this new BC I've been starting on different days than usual and I still have 6 of the green pills left. Should I be worried, or is this caused by my BC & stress? I have been on BC for almost 5 years now. My last period was heavy like always And I'm having all the normal cramping that I would with my period but it hasnt started yet...my stomach is cramping really bad and I really don't think I'm pregnant but I'm really confused! And I had to repost this with more detail because I left some things out.