My cat Tiger is 20 yrs. old. He is very picky. He won't eat dry cat food. He lost a lot of weight. So we started buying can cat food, all different flavors. He kept getting pickier and pickier on the flavors. He will only eat one flavor now and I have a hard time getting it as it is a store brand of cat food. We've tried every kind of cat food. He seems fine other than being skinny and picky. Any suggestions?