Only thing I could suggest is to get him thoroughly examined by Pediatrician
and do laboratory investigations if he/she suggest.
Fever in this age group have multiple causes. Infections in- respiratory, urinary, gastrointestinal systems are common. Other causes are - Sepsis, malaria
, typhoid, dengue etc.
Investigations like - Blood for Blood count (CBC), C-reactive Protein
(CRP), Blood culture
& sensitivity for suspected sepsis, Malaria parasite and antigen, Dengue antigen and antibody, WIDAL test
for typhoid and paratyphoid, Urine for RE,ME & C/S, Stool RE,ME, Chest X-ray etc may be necessary to reach diagnosis as suggested by clinical examination.
Clinical examination is the first and most important thing for diagnosis and treatment.
So, get your child visited by Pediatrician and do whatever he advise.