HI , My 6 year old son has a continous dry cough since two days , no fever and active but says the cough is really irritating him . have been giving him a syrup containing , dextromethorphan hydrobromide 5mg, bromhexine hydrochloride ip 4 mg , phenylepherine hydrochloride ip 5 mg, menthol ip 2.5 mg,------ two times a day . What should i do ?Thanks.