Welcome to Pet Talk! I'm sorry that it is under these circumstances.

I'm Sandie. I live in RI, with 4 dogs, 10 cats, and my father who is 81.

About your Addie:

Yes, take her in, don't wait for the other vet to return.

It could be kidney, diabetes, or even thyroid which is easy to treat with a pill per day. Other things, too.

Withholding water will just give more issues as she will get dehydrated.

MOST of the things which it 'could' be can be diagnosed via blood work. They may also want a urine sample for a urinalysis.

Please don't wait, as some things are easier to treat the earlier they are caught.