Dej, I'm so sorry. I know how hard this must be for you....and for poor Jack. He's suffered so much.
I desperately wish you could find a vet that would say "just do this" and it would work.
I suppose the only positive thing in all this is that Jack doesn't have to suffer needlessly or alone. Some folks just ignore their pets and they suffer silently until the end. I'm so thankful you're there for Jack and truly concerned for
his well being.
Have you tried an holistic vet?
You're both in my prayers.