@gingerw had a lot of great suggestions regarding muscle cramps and CKD. I want to hone in on the mention of diabetes. I’ve been diabetic 50ish years and I have CKD stage 4. Poorly controlled diabetes can result in DKA (diabetic ketoacidosis). It can be life threatening and also involves some muscle cramping. A slower more subtle complication is diabetic neuropathy. This can be peripheral affecting limbs, especially feet and hands. It can also be autonomic which controls the internal organs (like the stomach and heart).
Do you have specialists caring for your diabetes and kidneys? Have you told them about your muscle cramping? Make sure you do so at your next appointments. Hopefully they can check for some of the terrible things I mentioned and also make suggestions of ways to ease the cramping.