I'm sorry to hear that you and your cat are going through this.

My cat recently went through something and I do think he was poisoning himself. I got all the plants out of his reach, and stopped him from going in attic, cellar, garage where poisonous stuff tends to congregate.

Indoor cats especially long for plants. I think it is probably nice to buy a cat-grass plant. I see them at the grocery store. Or start one of your own with seeds.

Egg yolks seem to perk up my cats over the long term.

Also, raw ground beef. If a cat is very ill, prob not a time to try raw meat. Start it when the cat is well.

The breeder says she would sometimes give whole milk yogurt to cats when they were "off" in the digestion.

hth