She is likely to have a viral fever. I would advise you to visit a MD general medicine so that she can be examined and undergo investigations such as Dengue IgM, WIDAL, Lepto IgM, etc. to find the underlying cause and have it treated accordingly. Kindly make sure that she's well hydrated.
Next Steps
Follow the steps as advised
Health Tips
If condition persists or worsens visit the ER at the earliest