Hello, my name is***** and I have over 20 years of experience as a veterinarian. I am sorry to hear that Sheila has a poor appetite, has been licking her nose and is shaking slightly. Her symptoms don't mean she is dying, but she is trying to tell you she doesn't feel well.
Shaking can be a sign of fear, but in her case is more likely related to nausea, weakness from not eating and possibly an imbalance of electrolytes and dehydration.
Lack of an appetite and licking can be related to nausea and 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, a dietary allergy or sensitivity, toxin exposure, a viral or bacterial infection, Addison's disease (hypoadrenocorticism), inflammatory bowel disease, or even infiltrative cancers such as lymphoma.
If she hasn't eaten normally in several days and if she isn't drinking normally either I am very concerned about her. Because if she isn't drinking well either she will quickly become dehydrated.
Ideally she would see a veterinarian today if 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 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 and drink. 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 and get additional fluids into her.
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.