I’m in the midst of seeing my GO and getting an ultrasound but curious if anyone has any insights or experience with cramps after their period ends?

I’ve been getting cramps for 3-5 days after my period ends and wondering what the cause is and how to manage it, the cramps make me feel quite tired also.

My cycle is reasonably long and somewhat irregular ranging from 35-40 days in length, I can never pinpoint an exact day I’ll get it, maybe this has something to do with it also?