What caused her upset stomach? What does a veterinarian that has examined her advise?
She may be nauseous, in that case, be glad she is eating anything and drinking adequate fluids (assuming that she is)
After a stomach virus (if that’s what it is), it can take a week or two for normal appetite to return, longer without treatment.
If she doesn’t eat or drink x 72 hours I would head to the emergency vet. She could have a blockage. There are a multitude of things that could cause poor appetite, only a visit to a veterinarian can determine the cause. How do her teeth look?
