Cramps

Roksana

I’ve had ovulation unusually early this cycle on day 11. I tested with OPKs. Now today is my cycle day 15, and apparently 4th dpo. I have really bad cramps and feeling drained today, craps are on the left side of my lower abdomen only, also mild lower back pain. Is this ovulation or implantation? Or what?

Ps. my Opk is negative today, checked just in case.