Spotting and cramping at 4DPO?

I know it’s too early for implantation, is it just the rise in progesterone? Is it my period starting early?

Anyone have this and still be able to get a BFP later? I’m worried my chances are gone. 😔

Edit: I had a positive OPK 5 days ago, so it seems unrelated to ovulation, but thanks for brainstorming.