Like Ron, I too work through the effects of M.S.. I had all but given up playing the guitar for thirty some years because of this, although unbeknownst as to the reason for the difficulties. I was inspired back to music whilst visiting Ireland some 4 ½ years ago.
The best advice has already been given. Take every scintilla of progress as a victory, leave every stumble in the meaningless annals of history, take respites along the way especially on the difficult days, and carry on.
When asked what it is that I attribute my ability to still walk to I respond simply that I can still walk because I do. Our bodies are amazing and they have tremendous abilities to adapt to changing circumstances. I am convinced, through personal experience, that desire is the foundation of rebuilding nerve pathways and function, or in the very least the foundation of finding new ones to rely upon.
As with Ron you are welcome to contact me directly. Best of luck on this journey. My prayers are with you.