Breakthrough bleeding

I have been having breakthrough bleeding like crazy. Last period cycle it went for a MONTH. It finally subsided but now I woke up after a horrible nightmare and my first day back to school as a teacher (and student, I take ASL night classes) and I completely bled through again, so I’m wondering if it’s stress induced...? I am so confused. I’ve been on Nuvaring for years now and it has never done this. Just hoping for some clarity.