with the history that you are giving,you didnt mention any other problem then fever
But we have to find out the focus of infection.lets say....does he have cold?cough?
is there any other problem hes going through.
you should get his blood tested for "CBC",also if your areas are endemic(common) for malaria
,you should get them tested as well.
if fever doesnt subsides then its wise to us antibiotic after detailed history and physical examination.
hope this helps.