My Son Is 5 Yrs Old. Having Cough. In Night

my son is 5 yrs old. Having cough. in night he breath with his mouth during sleep. and little temperature is also there, i gave Chest on syrup & combiflame syrup. but its effects only for 4 to 5 hrs so what should i give him. i also have Cetrizine Hydrochloride & Ambroxol Hydrochloride Syrup at home name ZCET-AM, so is it advisable to give that