Thanks for your query.
Your child is having fever
which is mostly viral in origin.
Pain in legs is a part of on going viral illness.
Give her acetaminophen
as per dosage for pain.
Give her plenty of fluids,fruit juices,coconut water,vegetable soup and soft bland diet so as to maintain hydration and nutrition.
She should take adequate rest for 2 to 3 days.
In case symptoms persist get her examined by pediatrician
Wishing your child good health.