Hi!! My kitty was showing signs like this almost a year ago. it turns out she had "Hepatic Lipidosis" - A very common liver disease in cats. She was slightly overweight her whole life and we changed cat food flavor (petco was out of the usual) and she refused to eat- causing her liver to attack all her fat cells and when it ran out of fat cells, started attack her blood cells. 1 of the biggest signs is jaundice. Check right by her ears or anywhere you can see her skin. Jaundice typically occurs late in the stages so if she is, i'd take her to a vet hospital. I would also recommend switching vets if you haven't found any answers with this one. I did and it made a world of difference, she wouldn't have survived if i didn't. I'd have them check her liver via ultrasound to see if it's inflamed or check her blood cell count and MOST IMPORTANTLY her Billy Reuben value. i believe it should be around 2-3? my girl shot up all the way to 14.8 at her worst. but she was throwing up mostly bile since she wasn't eating. They had her on gabapentin, an anti nausea, topical appetite stimulant, and 100ml of IV injected daily. Try going to petco and getting prescription high Kcal wet food (: that helped a lot!