Hello dear , I evaluated your concern in depth . * This is upper respiratory tract infection following some viral infection , fever & lethargy is due to infection only . * Certain precautions at home will make him faster recovery . @ avoid exposure to excess cold / polluted air @ proper diet with all nutrients to combat the pathogens @ antibiotics , decongestant syrups as per given by pediatrician @ cold sponging in case of high fever @ take hygienic care of the face part @ avoid to give all chilled items, biscuits , chocolates , ice creams etc @ keep record of temperature 4 hourly @ contact doctor immediately if fever increases, not play , don`t take orally enough , other systemic problems . Hope this will definitely help you to some extent . Feel free to ask any query in future at anytime . Thanks for using Health care magic . Regards dear .