Veterinary questions? Ask a Vet for Answers ASAP
Unfortunately we know that he has a chronic and progressive illness so we can expect the waxing and waning of the associated symptoms such as inappetence, nausea, vomiting etc. It is 'normal' that his appetite will not be as it used to be but it is reassuring that it is sometimes very good.
A prognosis is a 'best guess' based on lab results, symptoms, experience etc. It is really difficult to predict how long any animal has left but many owners find it useful to get given a rough estimate in order to better prepare themselves for what may come. We can prolong life expectancy by managing symptoms as best we can and providing i.v. fluids for as long as they cause a positive effect.