Early Period Cramping- anyone else??

My cycle is always very on time as well as ovulation. I have never been late in 10 years. But sometimes my PMS symptoms, like cramping start SO early. I’ve been feeling slight cramps since 6DPO. And I feel like my body is once again ruling out pregnancy already. How can I be experiencing period cramps so early each month especially before implantation can even occur? Does anyone else experience this? TIA