Thanks, Eric! He seems to be doing really well. He's walking normally, can get up and down stairs, and even wants to jump onto the bed and couch (which I'm trying to discourage). We've been doing short walks only, and I can tell that he's getting antsy. He doesn't understand why I won't let him gallop around the house with his stuffed gorilla. At any rate, this is quite mysterious. He's still not his normal, bouncy self, but that could be either the pain meds or residual discomfort. I'm going to call the vet tomorrow and get advice about how/when to reduce his medication.
It's all very strange. I just hope it doesn't happen again.
I think there is a good chance that it will go away, but then maybe always the chance that it could come back again. Several months ago Skippy had that thing going on where his back legs wouldn't work - didn't appear to be in pain, more confused that anything. I was very concerned and the vets just took knee and hip x-rays - I know it is something with his back. But it went away and hasn't returned - but I do worry about him. I'm so glad that Theo is feeling better.