Oh, dear, had a long post and lost it looking up this.
Having Trouble Affording Your Pet? : The Humane Society of the United States
If you can't get a second opinion ASAP just to see if there might be some error in testing, can't sell some things, put it on credit cards or get a loan on your house or car or none of the sites on that link can help, a surrender to a rescue organization would be my next effort. At least he might have a chance that way. Otherwise, probably the only thing left is to put him out of his suffering before he gets any sicker. I'm so sorry to hear that your little love is so sick and it seems so hopeless. For him to go that far down so quickly is scary. It sounds like he does need to be on IV's to prevent dehydration because if his liver failure is severe, likely the Cerenia won't help much or for long. And in the hospital, he can be given larger doses of Cerenia if that's not going to hurt his liver that much more. I'm so sorry for that sweet baby boy of yours - it is tragic and so terribly sad.