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You present a complicated and long history.
Your question has 2 parts.
1) are they just going to tell me that they don't know what's wrong again?
That is certainly possible
There are times when medicine is difficult - and not straight forward.
That is the challenge of medicine.
With that said, I am more concerned with your other question...
2) do I need to get her to a vet before that?
The answer to this - is yes.
The concern with the lack of appetite, water intake, and vomiting - is dehydration.
The other reason we become concerned with a history such as this is that cats that do not get their nutrition (either from a lack of appetite and/or vomiting, regardless of the underlying cause - can get secondary liver problems, (fatty liver disease - medical term for this is hepatic lipidosis) LINK HERE
Can I make an appt for tomorrow or do I need to get her to emergency care tonight?
That is difficult to assess without even being able to perform an examination.
If there is continued vomiting - that would be an indication for evaluation.
Continued vomiting will lead to dehydration and secondary complications with electrolytes and even blood sugar.
I am not certain if you are having a chat issue...
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