A similar thing happened to me last cycle (but I only tested on 10DPO and got a BFN). I had the brown spotting which I never usually get, lots of pain and then plenty of clots and a heavy AF. I am not on Vitex.

I had a chemical pg / miscarriage a few months ago but I was 5 weeks along so it was a bit different to this one.

Hugs to you, I hope your BFP is just around the corner.