Oh, your poor lad and poor you - you must be worried.
Getting him on the drip A.S.A.P helps shorten the attack. Your vet's right about the diet - I've got my cavalier who's got pancreatitis on Royal Cannine Fat Free and she has improved... but the packet says that it's not for permanent use. I'm looking into feeding a raw diet - I'll keep you posted.
Also my vet (whom I trust 200%) says that pigs ears, raw hide chews ect must be banned as they contain high fat content - the hide chews are coated with fat. I've substituted them for nylon chewy bones.
I do hope he feels better soon xx Thank goodness you have insurance. Has the vet taken bloods again?
Take care and give the fella a big cuddle from us - keep us posted as there isn't many threads on this subject on here.