Obviously, there is an ongoing significant problem. It is impossible to tell what it is from what you have described. A lot more information from a variety of tests is needed. It sounds like the doctors are going to go into your son's lungs to try to find the cause. Even with a child with airway obstruction, this can be done safely. I would speak to your doctor and ask any questions you may have about the procedure. If this persists and questions continue, you may consider a visit to National Jewish Medical and Research Center. We often see young children with similar problems.
all in all this needs to be delt with ASAP. the procedure itself is safe in most of the time, but it depends on the underlying lung condition and how bad it affected lung function. the procedure (bronchoscopy) simply is a tube with camera will be inserted into the airways to lokk at and to take samples including biopsies. if it's not answering the question he may need to have surgical biopsy.
hope the best for both of you and i hope you could have answers soon so he can get better.
COMMON TRAITS OF INDOOR AIR POLLUTION
Affected Household Members initials: ____ ____ ____ ____ ____
Dust on furniture / Visible in air
House odors
Allergies
Asthma
Sinus problems
Headaches
Sleeplessness / Light sleeper
Snoring
Sore throats / Colds / Flu
Itchy/ Watery eyes
Coughing / Throat clearing
Lack of Concentration
Depression / Irritability
Fatigue / Naps
Mold / Mildew in basement & bathrooms
Pet dander and odors
Smoking
Wood / Coal heater
Static Electricity
As you fill this in and realize how much is affected by your indoor air; maybe you should try an ionizing/ozone air purifier like I have. It's removed all respiratory ills in our family with 8 children 19 down to two.