what did your implantation cramps feel like ?

I'm about 12dpo and for the past 24 hours I've been having what feels like period cramps off and on , they come and go and the completely stop then come back and they are super mild . It's way to early in my cycle to be pms as I have a 35 day cycle but is there any way this could be due to implantation ? My period is due in 8 days . I've had no bleeding , just mild off and on cramping !