Thank you for your query,
The fever is not related to fall and head injury
If there is concission, there will be mental changes after the fall like confucion, agitation, memory loss
and alterations in sensorium.
Monitor for head injury problems like vomitings, alteration in behavior and if you find any abnormality report immediately.
For fever you can give Tylenol
as prescribed and if fever is continuing consult your Pediatrician
to find out the focus of infection and for basic evaluation.
Hope I have answered your query.