Thanks for the sentiments and tips. And yes, we have manipulated diet and tried different supplements. We see the vet tomorrow, so we’ll see what she says.
Oh, one last thing, you might want to try adding a teaspoon of cider vinegar to his water. It’s said to work.
The vet couldn’t determine the cause of his condition but is fairly certain it is progressive and neurological and not structural like hip displasia.
His brain and nervous system basically can’t control his hind legs and feet and he probably can’t really even feel them. She proscribed some some new pain meds that might help (slight chance) if inflamation is pinching his nerves.
We are also going to give doggie acupuncture and some chinese medicine a try as she said sometimes it helps. But she basically said keep him comfortable and manage his pain until he can’t relieve himself properly and then bring him in and don’t let him suffer.
So that is where we are at. Thank you, everyone, for your thoughts and insights.
poor doggie 
At least you did the right thing and took him to the vets.
My parents had similar issues with two of their German Shepherds (degenerative neuroopothy is a genetic trait in the breed). Eventually their tails and hind legs stopped working and while they weren’t in pain it became a quality of life issue. One dog took several months before he couldn’t keep his hind legs up while the other was several weeks. They both had to be put to sleep in the end.
The sad truth is dogs can’t remember the good old days they only know what it’s like today. I’m sorry for your situation and hope his progression is slow and painless. I have a seven year old boxer and am hoping when his time comes it is gentle and in his sleep.