My son since age 2.5 ,get this hacking dry cough. This usually starts of with cold and 3 or 4 th day cough gets bad and needs nebulization. Been to couple of doctors . Gave him preventive inhaler beudocort yet he need nebulization. On multiple occasion have given him asthalin inhaler every hour but no use . Gave him duolin nebulization cough reduced a little . Had also given him cough allex for 2 dats and montair lc kid..He is 7 years now. His xray came out normal. What should be his treatment . I am tired of running to different doctors any protocol to follow?