Thanks for consulting at Healthcare Magic. For allergic bronchitis you may ask your doctor to add long acting bronchodilator nembulisation like Formeterol or Salmeterol which may prevent recurrent episodes of wheezing, oral antihistaminic, montelukast and mucolytic combinations which prevent allergic response and helps in clearing chest of secretions. Episodes of cough, wheezing, chest congestion occur due to exposure to an allergens. You will need to identify what is triggering such episodes. It may be allergens like pollens, dust, mite etc, Some times chemicals like perfumes, mosquito repellents etc. Adequate treatment may not be as effective if exposure to allergens is continued. Also since your son is having this problem since two years it would be better if you consult pediatric pulmonologist for further evaluation.