Hi Dr Jan ,
Thanks for placing your query through HCM.
I can appreciate your concerns.
Though the chances ot illness being viral are still high, considering his young age & 5 days fever
without any definite focus of infection I would advise you to get blood tests (CBC,CRP) and urine -routine ,microscopy & culture as a minimum. Also test for malaria
if it is a possibility in your area. Please discuss with his treating doctor.
Hope I have answered your query.
If you have any further questions I will be happy to help.
Wish you son a good health.