I have 2 - 4 1/2 month old male kittens w/their spayed mother who came from a feral colony. One of the kittens stopped eating/drinking for 3 days, throwing up green bile & lost a lot of weight. Took him to a vet, got NO diagnosis for $72. They just wanted to order $150 worth of tests. Next day, kitty started to eat/drink, and soon returned to normal. Then his brother got the same illness, but this has lasted longer. He stopped throwing up, and is eating/drinking. He's lost 1/2 his body weight, still very lethargic. He has that "sick look" in his face. Can't get them vaccinated till they're healthy. Can't afford another trip to the vet. or FIP tests. Any suggestions? Should I start with a fecal test? I don't want to lose him.