Good morning Trish, I'm tagging @jenniferhunter to see if she is able to offer some insight or suggestions that might be helpful for you. It sounds like you have been dealing with the related pain for a long time. Hoping you are able to find something that helps soon.

@cocodab I had to look up Erb's Palsy and it seems to be a birth injury of the brachial plexus. Is that separate from your C5 injury? Am I correct in thinking the spinal cord is OK, and you have injuries to nerves outside of that? Do you have an injury at the C5 nerve root?

My experience is that I have Thoracic Outlet Syndrome (a compression of the brachial plexus) and I had an old injury from a whiplash that caused my C5C6 disc to rupture and collapse and bone spurs compressing the spinal cord. I had surgery at Mayo for cervical stenosis. I have been doing myofascial release with my physical therapist for several years for TOS before my spine surgery and for my spine condition and rehab. I have similar symptoms with tight neck muscles because of TOS that MFR helps. Some of the tightness comes from the body guarding the injury, and I catch myself doing that and relax my shoulders. The constant guarding creates tension in my neck and shoulder, and that causes misalignment or bad posture, and the body gets stuck that way. The spaces the nerves travel through between muscle and bones are small, and adding pressure there creates a problem. MFR might be something to try as it can help a lot of problems caused by compression in the body.

Did you have results from nerve and EMG testing that said the nerves were permanently damaged and the electric potentials were listed as zeros? There is a point where permanent damage happens. Nerves can sometimes recover after decompression through therapy, etc. and peripheral nerves ( those outside of the spinal cord) have some ability to regenerate. I had some damage because my spinal cord was compressed for 2 years and I've recovered well. I did loose a lot of arm and shoulder muscle that I am still working to rebuild, and I've probably regained a little more than half of what I lost in the 2 years since my surgery. I did not have any nerve root compression, but with my disc that had collapsed 50% of it's height, if I was side bending my neck, the bones would touch the nerve root and send sharp pain down my arm. Sometimes spine patients get arthritis or bone spurs in the area around the nerve roots
where they exit the spine.

Here are some links that may be of interest. The first is about peripheral nerve regeneration. The last link is from an MFR expert in the John Barnes methods that lists Erb's Palsy as something that MFR can treat.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2770804/
https://trainingandrehabilitation.com/how-truly-treat-thoracic-outlet-syndrome/
https://monadnockmyofascialrelease.com/who-benefits-from-mfr/