I have 2 kittens (10 weeks & 5 mos). One of them has diarhrea and I'm pretty sure it's the 5mos. old persian. He's free fed Chicken Soup dry food for kittens and has VERY little of Merrick's natural canned food. He prefers dry. The other kitten could eat the canned food forever! How do I go about finding out what's giving him the diarhea? Should I eliminate everything in his diet except the hard food to see what happens? How long before I should expect to see results? Thanks for all you advice fellow cat lovers!!!