Leg Issues

I had surgery in January to remove a cyst on my spinal cord that had disabled me for several months.
Now, I can walk but I still have problems with my left leg. If I walk for more than about ten minutes, my leg becomes heavy and very tingly. It then becomes extremely difficult to walk. I'm told by the neurosurgeon that there is no nerve compression but I don't understand what is causing the continuing problems. I also get very tired after physical activity. Sometimes for one or two days afterwards.
I have also been diagnosed by Mayo with autoimmune encephalopathy but I'm not aware that this could be connected.