Calf pain can be seen in viral fevers.
You may give her Acetaminophen
in dose appropriate for her weight every 6 hrs.
If pain is severe, you may give her one or two doses of Ibuprofen
Also give her plenty of fluids and bed rest
With these she should be fine.
However in view of the travel plans you have, its better to have a word with your Pediatrician
and get her examined before you travel. You might need to carry all the medications needed when you travel.
Hope I have answered your query.
Wish your daughter a speedy recovery.