My baby is ill

My baby, Amos, has been sick. He was in the kitty hospital for 6 days. They did every test on him - even barium x-rays. They have no idea what is wrong. He's still sick. He wasn't eating/drinking at all. He started to drink small amounts before they let him come home. He ate about 4 tablespoons of food for me today, which was the most he has eaten in about a week and a half or more. If he can't start eating soon, he will have to go to a bigger vet with more tests about an hour away. :(