Hello, my name is***** and I have over 20 years of experience as a veterinarian. It sounds like Knotty has a poor appetite and is losing weight but her water consumption has been ok.
Lack of an appetite and weight loss can be related to eating something she should not have such as eating foreign material (which could cause a full or partial gastrointestinal obstruction), chronic pancreatitis, toxin exposure, a viral or bacterial infection, Addison's disease (hypoadrenocorticism), inflammatory bowel disease, organ failure, diabetes, or even cancers.
Because she hasn't eaten normally in several days and is actually losing weight I am very concerned about her.
Ideally she would see a veterinarian today since this has been going on long enough to cause weight loss. Simple stomach upset should pass within 24 to 48 hours. They could examine her, run blood tests and possibly check radiographs and/or an ultrasound to evaluate her and know best how to treat her.
In the meantime they can administer injectable anti-nausea drugs and fluids to properly hydrate her and balance electrolytes.
If you cannot have her seen for a few days for whatever reason there are some things you can try at home.
At home to try and settle her stomach you can give either:
1) Pepcid ac (famotidine) at a dose of one 10mg tablet per 20 to 40 pounds of body weight every 12 hours
2) Prilosec (omeprazole) at a dose of one 20mg tablet per 40 to 80 pounds of body weight every 24 hours
These are acid reducers and may help her feel less nauseous so that she will eat better. They are quite safe and can be used for several days if necessary.
A couple of hours after giving the acid reducer I recommend offering meat baby foods or a bland diet of 1/3 boiled, minced, white skinless chicken or boiled, lean hamburger and 2/3 boiled white rice mixed with some low salt chicken or beef broth to make it easy to lap up and swallow.
If she continues to not eat she should see her veterinarian for an examination, diagnostics and intravenous fluids and supportive care.
Please let me know if you have any further questions.