Unexplained nerve damage & leg weakness years post-op?

I had a successful scoliosis revision surgery in 2021. Almost four years later, I began noticing painless right leg weakness with some cramping. I started weight training to strengthen the leg. The weakness grew worse. I returned to my surgeon and had imaging including MRIs, CT, Myelogram, X-rays. No abnormalities pointing to a cause. I’ve now seen multiple neurologists, had 2 EMGs, genetic testing, CSF testing, and bloodwork. EMG was abnormal and confirmed nerve damage. Still no diagnosis. Now, almost a year after my first symptom, I am unable to walk without a walking stick and I cannot ascend stairs. I’ve fallen multiple times due to my right leg buckling. No injuries. Every doctor says this is a mystery. As such, I’ve received no treatment except PT scripts. Any and all hypotheses welcome!