What do you feed a cat that doesn't like anything??

Ashten, our hyperthyroid kittie, has decided that he doesn't like cat food anymore. We were feeding him Friskies and 9 Lives (I know, not the best food in the world :/). Ashten decided he didn't like anything else, not even good gourmet stuff. And now Ashten has decided he doesn't like those either. Siam mostly eats the dry food, and Ashten nibbles the dry food. His weight is slipping because he won't eat! Ashten will eat chicken (that's how we give him his pill every day), but I don't think that's total nutrition for a cat. He is just so picky, I don't know what to do!

Has he been to the vet regarding his not wanting to eat? What is the pill he's taking? He could be nauseous or not feeling well rather than just being picky. The weight loss is concerning, and I would definitely talk to the vet--they can prescribe an appetite stimulant as well as help find out why he's not eating in the first place.

The medicine Ashten takes is Tapazole, its chewy. He just had his levels checked about three weeks ago, and they were low so the vet upped his dose. Ashten used to get half a pill twice a day, now he gets 2/3 in the morning, and a half at night.

If his stomach isn't feeling well, why does he eat chicken with gusto, but barely touch anything else?

I'm guessing his levels were high, not low, right? Tapazole is for bringing down high levels.

Have you checked his mouth? Sometimes when something is off, like a loose or broken tooth or inflammed gums, they won't eat their normal foods because it hurts too much. They might still eat the "special" foods because they can't resist.