Making your own food
I don't have a cat so don't know much about them but...
I have Westies and two were having a lot of stool problems and one was itching.
After many $'s spent at the vets. and still they were no better I started doing my own cooking for them.
I had to cook different things but came up with a meatloaf that is working great.
The fur look is thicker, no itching, and stools ate as should be.
I do give a good vit, with minerals just to be safe.
I have a opened minded vet, she looked the meatloaf over and said don't know why it's working but keep it up.
So give them a top of the line vit, and cook away is what I would do.