I’m so sorry; we lost our cat just this week in similar circumstancces. Stopped eating, lethargic, rapid weight loss. Took him to the vet and assumed I’d find out he had a hair ball or diabetes or something treatable.

Ended up being cancer and we had to put him down. I loved that damn cat. He was also 11 years old.

So I am hoping and praying your cat has something easily treatable and can be with you a long time. And the financial stuff is hard; we spent quite a bit for the diagnosis and then had to lose him anyway.