Has your vet run a bun and a creaton (sp?) level test to see what the kidney and liver are doing? Did your vet say what the food intact should be for a puppy his size? Maybe every 2 hours is to much?
What vaccinations did your pup just have? Did they use Lepto?
Did you put any flea/tick meds on this puppy?
The next question I would have is who is your vet? Patti on here is very aware of Liver Shunt and she has some great vets who are well aware of this birth defect.
http://www.livershunt.com/
I don't mean to scare you but it appears you have tried everything to get this little one to eat. The only other suggestion would be to water down or use broth in the dog food so it is softer as maybe he has teeth problems.