Charles, I'm beginning to think you're right in this case.
Today, after several days of what seemed like improvement, Stitch has become very lethargic, and almost completely unresponsive to touch. I'm afraid I am going to have to break down and admit defeat here. It doesn't look good.
I don't know if I have the emotional strength to just put him in the freezer though -- I'm still trying to talk myself into being able to do that.