Can anyone please explain the feeling of implantation cramping? Is it similar to any other cramping you can link it to? Cramping feeling of needing to go to the toilet? Niggling feeling in lower belly? Pressure feeling?

Kind of feels like period cramping in my lower back what I'd usually feel a day or 2 before my period + niggling feeling above my bladder... still 8 days til my period is due though so can't be my period.