Fever, headache, stomach ache, less activity and low appetite- may be she has a viral fever
Since its almost 3 days now since she is unwell, its wise to see your doctor. Your child has to be examined fully and if needed investigated to find out the cause of fever.
For fever, give her Acetaminophen
in a dose of 15mg/kg/dose, every 6 hours.
Give her plenty of water, vegetable soups and fruit juices, that will help in softening of the stools.
And do see your doctor.
Hope my answer helps you.
Wish a speedy recovery for your little one.