Symptoms described by you suggests that he has a allergic tendency as you rightly pointed out . But if his requirement of nebulizers is more than twice a week then his medication needs to be stepped up and try to asses if there are any triggers for the same and avoid it. This can be done through allergy skin testing. Which will identify the triggers and avoiding which may control his allergy. Frankly speaking I am a allopathic doctor and I donot think there is a cure for allergy but yes can be controlled and at a later age it may settle.