Diegosmom- I wanted to respond to your thread but it was already closed. Have you tried researching stifle problems on the internet? I am new to gaited horses but I have researched them a bit since I own a Fox Trotter and one thing that I keep reading about is that they can be prone to stifle problems due to traveling in an inverted frame. So I don't know if this is what your walker has, but I thought I would mention it in case you haven't researched it yet.
To me he looks weak in the hind end but not on deaths door. So many people on the forum are downright rude. I would try to find a vet familiar with TWHs. For instance some people were commenting on him being narrow but that is very common in TWH's and generally speaking it doesn't seem to be a problem. Anyway, I hope you can get him back on the right track because he seems like a lovely horse! Get a good vet familiar with your breed and try researching "weak stifles" as it pertains to gaited horses. Best of luck!