I now have two vets trying to puzzle it out. He was better last night so we're taking a "wait and see" attitude. The second vet said that maybe using a calming med (gabapentin?) at night might help. On top of it all Jake has now been diagnosed as being diabetic. It's a twofer!
On edit:
makes me wonder if all the water he drinks is messing with the thyroid drug's effectiveness??
He's been tested a couple of times and it seems fine. The vet is supposed to call me Wednesday and see how he's doing. I'll ask her if that's a possibility. Thanks.