... so your son has had various viral illnesses. All of which affected his respiratory functioning.
He's had Croup, RSV, and possibly viral induced Asthma.
Croup, is NOT the same as Asthma. Different illness and different symptoms.
These are all different illnesses. Viral. But has produced, Asthma like symptoms and breathing aberrations in him.
Any bad respiratory or upper respiratory illness, can affect breathing and produces coughing, mucus, wheezing, etc. And it can also develop into Bronchitis of which there are many forms and/or Pneumonia and/or Asthma etc.
And he had RSV. Which is bad. Too.
Inhalers, are Bronchodilators. It opens up constricted airways. So that breathing ability eases. It does not "cure" a cold or cure a virus.
Steroidal inhalers work for bad cases and reduces inflammation of the airways more immediately. Inflammation of the airways, is constriction of the airways in the lungs. And it reduces breathing ability.
Croup, also causes constriction of the airways and its symptoms may SEEM like Asthma. But it is not the same as Asthma.
Yes, you should see a pediatric Pulmonologist.
I have Asthma. But each person with Asthma will have or may have different triggers. Asthma episodes and attacks can be caused by environmental things, ingested things, or by colds or by weather or exercise etc. For example.
My son also had Croup once. But he does not have Asthma. It is 2 different illnesses. But it has to be treated.
His Croup, also caused an eye infection.
Is your son in Preschool?
Young kids can often get sick, often.
But the bottom line is: since your son has had bad colds which affected his lungs, you need to see a Pulmonologist. And get specific, treatment PER your son's condition(s).
And, when/if, your son cannot breath or struggles to breath and/or is turning blue on his lips or fingernails etc., that means his oxygen levels in his body and system, are inadequate. THUS, you should take him to the ER and/or give him his inhaler right away.
This is then an emergency situation.
Being your son, has been sick a lot and his breathing ability reduced and impaired... you MUST ALWAYS have on hand... his Inhaler and any other Doctor prescribed medications, at ALL times. And/or even taking it with you and having it on hand, wherever you are with your son.
Has the Doc ever recommended a nebulizer for your son?
And, you must always be observant for any secondary infections in your son... whenever he is sick.
Then, an antibiotic should be prescribed as well.