Cramping-4 dpo

Okay. I THINK I'm about 4 dpo according to Glow. I got a positive opk last Wednesday afternoon so I guess that'd mean I ovulated last Thursday. I am having crazy cramps right now. They're bad. It's surely too early for implantation right? And my period isn't due for a week. Usually I'll get cramps the day before/day of my period. But never a week before. Any insights???