Period in middle of fertile week?!?!

Karisma
So I'm on CD 13, currently ovulating, having ewcm. Woke up this morning and I'm bleeding....mildly, but bleeding. More than I would expect for implantation, though. Yesterday I didn't take my bc until late, but I've skipped days before and it never caused a mid-cycle period. I'm so confused and worried! Any input?