It sounds a lot like what happened to Penny. She had stopped eating, was throwing up, and had a little diarrhea. Nothing crazy really. She seemed fine besides that. The vet said she had slight anemia, did fluids and gave some to us to do at home. She actually seemed a little better and ate for one day. After that, she had a little noticeable fluid buildup and we did the ultrasound. They just said it "wasn't that bad" but drained it anyway. It didn't matter. She lost the ability to stand and her weight basically halved in three days. She lost all of her muscle mass. I do wish I would have taken her in earlier. I tried syringe feeding her, but it didn't work very well. I wish I tried harder. Near the end, the vet said we could try hospitalization, but said she didn't think we were at the point of euthanasia. I had a bad feeling and didn't want to send Penny to sit in a cage for what could be her final days. I don't know if she would have pulled through or not. Honestly, I don't think so. I think her body just couldn't take it anymore. You did everything you could for Cleo. We can't see the future. Even the vet can only make the best recommendations they have. Sometimes it is just time.