Hello, Your son s condition is due to the obstruction in his air passages due to mucus plugs which get deposited in his airways and hence he feels difficulty in breathing and start coughing to dislodge it. I advise my patients with such symptoms to take mucolytic syrup so that the secretions can dislodge it easily without frequent vigorous coughing. Moreover, he may have pain in his chest muscles so a good muscle relaxant and painkiller would be required as per need basis. Increasing the inhaler quantity to the above mentioned dose is safe but if his symptoms are not improving then go for nebulization. Hope I have answered your query. Let me know if I can assist you further. Regards, Dr. Maryum