14dpo... Heavy bleeding

Hey guys! So I'm 14dpo and 6 days before AF is expected... Yesterday I started lightly bleeding and today it turned into a heavy bleeding enough to fill a super tampon. I've been off BC pills for 6 months now and I'm unsure of what this could be. This bleeding is bright red (tmi sorry!) with faint to no cramps and no blood clots... My boobs are slightly sore which they are never during my regular AF days and my back hurts... Any advice would be awesome!