21 weeks on and off cramping

Mary

Any one else going thru this i just turned 21weeks monday but I've been having on and off cramping for almost two weeks already at first i thought they were BH but today they are getting worse more painful and lasting more than 1minute the thing is that I'm getting them every hourr or so not consistent. I was in mexico for two weeks got back on the 12 of Aug my ob did blood work but everything came back normal ultrasound looked great this is baby #6 and this never happened with any of my other kids ones the cramping starts the pain goes all the way to my lower back and my legs and really really painful