Hello, my name is***** and I have over 20 years of experience as a veterinarian. I'm sorry to hear that your girl Princess isn't eating well over the past week and is getting very boney.
Not eating can be related to eating something she should not have, too many treats or table food, eating foreign material (which could cause a full or partial gastrointestinal obstruction), chronic pancreatitis, esophageal reflux, a dietary allergy or sensitivity, toxin exposure, a viral or bacterial infection, inflammatory bowel disease, heartworm disease, hyperthyroidism (a tumor of the thyroid gland) internal organ failure, or even infiltrative cancers such as lymphoma.
At her age unfortunately we need to consider more serious things like organ failure, or cancer.
Because she hasn't eaten normally in several days I am very concerned about her. If she isn't drinking well either she will quickly become dehydrated, and as her liver breaks down fats for energy to live she may develop a type of liver disease called hepatic lipidosis. This is when the liver becomes overwhelmed with fats as it tries to break them down and is unable to perform its other normal functions.
I know you were looking for ideas to help her other than a veterinary visit but ideally she would see a veterinarian today since this has been going on for more than 72 hours. 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 rehydrate her.
If you cannot have her seen for whatever reason there are some things you can try at home.
At home to try and settle her stomach and improve her appetite you can give either:
1) Pepcid ac (famotidine) at ¼ of a 10mg tablet per 5 to 10 pounds of body weight every 12 hours
2) Prilosec (omeprazole) at ¼ of a 10mg tablet per 5 to 10 pounds of body weight every 24 hours
These are acid reducers and may help her feel less nauseous so that she will eat. They are quite safe and can be used long term if necessary.
You can use a medicine syringe to try and force water into her orally.
A couple of hours after giving the acid reducer I recommend offering meat baby foods or a bland diet of 2/3 boiled, minced, white skinless chicken and 1/3 boiled, white rice mixed with some low salt chicken broth to make it easy to lap up and swallow.
But 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.