I’ve had lower back problems fro 40 years. MRIs and EMGs indicate the loss of feeling in feet and lower legs is a result of Arthritis and Spinal stenosis, etc. I am overwiegt, use a CPAP but am not diabetics. My heart is fine, I take no prescription meds. Over the last several months I am awakened 4-5 times/night by cramps in my feet and lower legs. At least a few times I need to stand in order to relieve the cramping. What could be contributing to this cramping that only occurs at night?