My girl 3 years old has a fever with no other symptoms. only fever ,feeling fatigue & sleepy. she also refuses eating.. what's the reason?

Viral?: Your baby most likely has a viral illness that is causing some nausea so she does not eat. She may have less fatigue after her fever comes down and you can do that with Tylenol (acetaminophen). If she still continues to refuse to eat, try to give her small sips of fluids so she stays hydrated. If she gets worse or you cannot get her to take fluids, she will need to see a doctor.