SEVERE cramping 7DPO

Has anyone else experienced extremely severe, doubled over AF type pains at 7DPO? With my first I had implantation bleeding but no cramps and this is happening now right around implantation time. It lasted only about an hour but I was in such pain I had to rush home to curl up into a ball. As soon as I did that, they went away. I rushed to the bathroom when it started, thinking surely this is AF arriving but it turned out to be heavy watery, slippery CM. Any thoughts ladies?