Oh I am so sorry to hear this. is there family that you could ask help from, I know when Charlie was so sick I took a loan from my 401K to pay his bills I was glad to have that to borrow from but even at that I borrowed form my mom and it was $5000 easy when it was all said and done. Did your vet do any Xrays? an ultrasound or anything? I would be interested to see his lab results.
I would like to suggest you call Univ of Tenn they specialize in liver problems Dr Tobias is an expert and they helped me when I called them about Charlie. They were very kind.
Portosystemic Shunts
You certainly dont want him to be in pain so keep that in mind when you are deciding his care. these little ones are so precious so much like family, my prayers are with you, please keep us informed.