sharp cramps

I am on cd20 and I'm 4-5dpo. This evening I started getting sharp cramps, first on one side, then later on the other side. They've been alternating all night. I do tend to get mild, dull cramping about a week before AF but these are way more painful and occurred sooner than expected. This is my last cycle for awhile on Femera and it was my 4th IUI. Could this mean anything? Has anyone experienced this before they conceived? Thanks!