Have you been checked for spinal stenosis? It seems like your spine is having the problem too. I hate to mention it but could it be tumor or something. Research spinal stenosis and peripheral nephropathy and see what I am referring to. I have had all kinds of tests and no one has even mentioned this connection but they never can find out what is causing mine. I am going to pursue this as a possible cause. BTW, I have had this for 15 years and it is getting worse every year. So, I am more than motivated because of the pain.

@ericvnelson I would agree that you should consider have an evaluation for spinal stenosis. It can sneak up on you and happen years later after an injury like a whiplash. I had spinal stenosis in the central canal at C5/C6 and it did cause significant muscle loss (in my arms/shoulders) and intermittent drop foot. I also had some instability and muscle spasms taking the curve out of my neck, and when my physical therapist got things realigned, the drop foot stopped happening. The spasms moving my vertebrae around effectively made the small canal even smaller. It was progressing rapidly with bone spurs and the collapsed disk digging into my spinal cord. I saw that double in 9 months time on my MRIs. I had surgery at Mayo and it fixed all of that. Do your homework on good surgeons, as they are not equal. My surgeon at Mayo was excellent, and I had great results. If you can go there, you would get it figured out a lot sooner than waiting for multiple appointments somewhere else. It took me 2 years of getting worse and no one would help me, so I contacted a surgeon at Mayo.
Here is my story. https://sharing.mayoclinic.org/2019/01/09/using-the-art-of-medicine-to-overcome-fear-of-surgery/