Miss Kitty ate well this morning. We went to see her (and my) favorite vet. She had lost 1/2 pound since last month, but that was to expect. The vet listened to her heart and found no murmur, hooray!
Her theory is that, after Miss Kitty's inappetence and diarrhea, she became dehydrated, which affected her kidneys. We'll never know what caused the diarrhea, but it seems resolved (her last poop was Sunday night). I just have to watch her for constipation (which she has dealt with for several years).
I gave her some more SQ fluids, and she's supposed to stay on anti-nausea meds.
So overall, she doing pretty well.
Thank you again for all your well wishes and positive thoughts. There's no doubt in my mind that you all helped Miss Kitty (and me).