side effects

My son was put on Advair 500/50 due to a chronic cough last year. He is now 9 years old and many things have changed in him. He seems like a different little boy, he upsets very easily he gets very angry, he wakes up a lot during the night he has a hard time sleeping and now the cough has gotton worse. Today he is scheduled for a bronchoscopy. I was wondering if it is possible that the medisnce caused a build up in his lungs? The doctor thinks there may be a blockage. How long is too long for thius medicine? My son has had this barking cough on and off since he was little. Worse different times of the year. He does not wheeze or complain of not being able to breath. He never has to take an inhaler. He plays all sports and runs around like a normal very active boy. Should he stop this medicne and maybe try something else for the cough that happens different times? thank you, Marybeth