It is looking like upper respiratory tract
infection as there is running nose, cough and throat irritation
and looking like viral illness and not looking like whooping cough
. What is the status of your child immunization against whooping cough? If he recieved the regular vaccination approprate for his age nothing to worry if he exposed to whooping cough. Children below 6 years will swallow the phlegm and they cant spit it. Child appetite will improve as he recovers from this illness so consult your Pediatrician
for medication advise and for a speedy recovery.