Hello
I have gone through your query and understand your concern.
Severe fatigue,sweats ,nausea and increased
WBC count can be due to any infection present in body.It can be viral or bacterial.
Basic blood workout and detailed physical examination by physician needs to be done first.
He needs to undergo investigations like blood smear for
malaria,
Widal test for typhoid,liver function tests for
hepatitis,urine test for urinary infection.
Any infection can present atypically in this age.
Offer him with plenty of fluids to maintain hydration.
Small frequent meals and soft to semi solid well cooked food recommended as he has loss of appetite.
Further management depends upon the diagnosis.Antibiotic course may be needed for 7-10 days.
Hope I answered your query.
Wish him good health.
Thanks and regards.