Thanks for your replies.
LBass, he still wants to get up as usual when I am preparing his food and when I leave the room. He struggles to get up beyond what he is physically capable of. It's like he doesn't admit that he is having difficulty. He still wants to go out, but now he needs help. I had the stairs removed and had a big ramp built from my back deck a year ago, so he doesn't have to face stairs.
He can't take Gaba, has a bad reaction to it. I recently started giving him Previcox, and it helps, so he is in some pain. My favorite vet moved some distance away from my regular practice and the remaining vets are missing diagnoses on my other babies. Our emergency hospital has a lot of specialists: neurologists, radiologists, cardiologists, etc, and they are more aware of current best practices. I have more faith in them than the vets.
My google searches have always said there is no treatment for DM. But recently I found aminocaproic acid, which might help some. Was hoping someone here might know something. Will ask the specialists about it.
He loves the warm sun in the spring beyond anything. Hope he can hold on for another few weeks to see all the beautiful alpine flowers that carpet our acre in the early spring.