Senior Cat- Struggling with Appetite

Hi everyone! Kinda looking for advice on appetite in senior cat following high ALT levels.

Cat, 15 years old, spayed, 8lb (used to be 11lbs). Located on Maui

A little back story! Kinda long but feel like its important.

August 21st I took my 15 year old cat to her vet for a suspected upper respiratory infection. At this appt they did note her yellow tinged ears, but didnt push for any bloodwork. They prescribed Doxycycline for 2 weeks. That was a huge mistake.

The 2 weeks were filled with constant nausea, puking and towards the end of the medicine, a loss of appetite. I didn't realize that she hadn't eaten anything (as we unfortunately got a new kitten at the same time, love my kitten but really feel bad for my older cat now). She would refuse tiki wet sticks (used to be her favoirite) and any look at her dry food. She would gag and turn away.

September 9, I called her Vet and got prescribed Mirataz. That didn't work and on September 11th, I called the other vet in my area and took her for an emergency appt. They suspected maybe an irreated throat. They kept her for a few hours to sedate and do bloodwork and xray.

Her xray showed a mass in her stomach cavity, her blood test showed high calcium (higher then the vets test would count) high alt, high SDMA and high creatine. They kept her overnight for fluids and the next day i went to see her. They had gotten her to eat some churu sticks and about a tablespoon of wet food. The vet suggested putting her down that day, I said no and we took her home. Shes been on presidone since then. (We had a check up on the 17th and her mass was basically gone and all her levels were going down/normal besides her ALT)

She slowly started to eat some churu sticks and was able to get her to eat small amounts of tiki cat meal replacement and bone broth. I tried so many different wet foods, brands and types. She likes the fancy feast flaked but will only eat around a tablespoon or two (only at night time, I offer all day, but only eats in the middle of the night). Ive tried heating her food up, food toppers, mixing in her churu sticks, soaking her dry food, ect.

She goes feral for churu sticks!

She does not like the new kitten and I feel like this has caused more problems in her appetite. She doesnt hide from the kitten, just quietly growls at her, but won't let her near her. She'll explore the kittens room but gets extremely jealous when the kitten is on me or my partner. The kitten is in her own room at night, and when nobody is home. So she gets plenty of time away from the kitten.

Does anybody have any advice on getting her to eat? Is there any treatments I can ask the vet to do? Saw someone reccomned a feeding tube?

Could eating more help her alt levels?

Thank you!