I need advice from all you prog pessaries experts please

I am taking 3 a day of prog 400, and ever since I started yesterday, I have had cramps in my uterus and bottom, they were shooting up into my tummy. I rang the nurses and she wasnt much help, said she hasnt heard of the pess causing cramping etc, I have taken two panadol and that seems to have eased it, but I wonder what all this cramping is and as its quite uncomfy, and still happening . I dont feel like I need to go to the hospital at this stage, I just wonder if you guys hace had these symptoms...

Your advice would be greatly appreciated