I rushed Tenzing to the vet's this morning. It doesn't look good. He was carrying his right front paw limply and screeching to wake me up at 5am today, and I hoped it was just a physical injury. The vet believes we are looking at either a catastrophic neurological problem, a stroke, or something physical like a slipped disc that would cause numbness.
He's in a great deal of distress right now. I asked the vet to give him a sedative to help him calm down, and brought him home. He's currently on my bed, clearly still distressed but calming a little. I'm hoping he'll sleep if I don't hover over him.
We can pursue a CT scan to rule out repairable physical injury, and I'm inclined to go that far, as it's non-invasive. If it is neurological, the decisions get tougher, and entirely revolve around quality of life. If he cannot be a happy and comfortable cat, then I have to be realistic. Tenzing is nearly 14 years old, has a heart condition that is untreatable and eventually fatal, and ... has had an amazing, loving, cared-for life.
It may be time to let my kitty-kid go. It's not what I want, but I've known since early 2011 that this was a possibility. In adopting him I promised to make the right decisions for him, including this one if the time came.
More updates when I have more information.