Thank you for the suggestions everyone. He has actually been in a towel, on handwarmers/hot water bottles all night long. I took his temperature. It was 96.2. Now, he is in front of a HOT portable propane heater, on handwarmers, under a towel with a pan of hot water under it (for humidity), and he has had warm nutri-cal mash. He seems to be doing a little bit better. When I woke up at about 6, he was rolling his head around and gasping. That had me super worried, because I've seen dieing chickens do the same. I think that the propane heater is really helping.
Chickenaddict: That sounds like a good treatment, if it worked. I'm glad your hen is doing well.
mypicklebird:No, she didn't. It was considered, but there were several reasons why it was impractical at the time. If/when he has his next visit, we are planning on doing it. Would those other causes of seizures respond to the phenobarbital? His seizures seemed to respond. Thanks for your help.