Cramps AFTER ovulation

My husband and I had unprotected sex 5 out of 6 days during my fertile window.  I have cramps similar to menstrual cramps and it's been 4 days since ovulation. It's more painful on the left side and it's been on-going since yesterday. Has this happened to anyone else? Is this implantation cramping? I thought that didn't occur until 6-12 days after ovulation. Thanks