hi.. thanks for using HCM..
you 3 year old child has lower respiratory tract
have you vaccinated the child with pertusis vaccine?
see your peadiatrician.. need to undergo certain blood tests like CBC, ESR
, CRP, chest x ray
start with broad spectrum antibiotics with cephalosporins..antipyretics and other supportive therapy, need to take care of his nutrition..
after 1 week start with probiotics, and multivitamins..
all the very best..