I have asthma, since a child. I am now in my 40's. I still have it. I eat very cleanly and healthy. I still have it.
My parents kept my room as clean as a protective bubble... I still have it.
EVERY person is different and different in what reacts/triggers their asthma.
MEANWHILE, know that asthma is dangerous. You can die from it. It is not just a willy-nilly coughing problem. And the degree/severity to which a person has asthma, varies.
Know this, when your son is having an asthma attack or bout of it... you MUST give him his albuterol and Pulmicort. Or, you are neglecting his safety and health. A person can SUDDENLY suffocate from asthma... and die. My Doctor, has had a couple patients whereby an asthma attack came on so suddenly that help did not come fast enough, and they basically asphyxiated.
Now, imagine, that you cannot breathe and each breath is a BIG struggle, and each labored breath is like squeezing a tennis ball because your lungs do NOT expand fully to suck in enough air, and that it stresses your heart because each breath taxes your energy and system so much, that even walking 5 feet in the house can put you out of breath completely and you have to sit down, that even running can make you pass out, that when there is decreased oxygen in your system it also means decreased oxygen in your bloodstream, that each cough is a struggle and it means that coughing is triggered because it helps you take a breath...
Imagine, putting your face, face down in a pillow, and THEN try to take a FULL breath. Can you do it? What does it feel like? THAT is what asthma can feel like, when having an episode.
So, yes, research what triggers your child's asthma. I did that too. BUT do not do it at the expense of omitting his prescribed medications. That is doing him no favor... just making it harder on him and his body. Talk with your Doctor about it... in TANDEM with keeping up with his medication schedule. You may have a hard time with wanting to give him medication...but for your son, it is a "life-saver." Literally. Your Doctor is not "forcing" medication on him... it is therapeutic. And probably, he will only need to take it when his asthma acting up. Later.
My Mom, used to think that my asthma was just coughing too. Until she came down with a BAD episode of Bronchitis with which she had Asthma symptoms & almost ended up in the hospital. ONLY THEN, did she realize what "I" went through during an asthmatic episode. NOW she sympathizes with me.
For me, dairy is fine. It does NOT affect my asthma.
What affects ME, are the sulphites in dried fruit and wine, and cured meats.
Another thing is, if you do not give your son his medication, when he needs it... you must realize that in the long term... it can permanently cause lung damage or lessen the lung health of his body. Thus, these asthma medications are for a purpose.
Sorry to sound so emphatic or direct. But, I am an asthma sufferer as well... and so I just am directly affected by it as well.
Take care, but always get the guidance of your Pediatrician and gain knowledge about it. Or your son will get worse.
Some people can only go about it nutritionally/food wise... but others, depending on the severity of it, HAS TO take medication. So, analyze it in light of your son's health.
AND you might want to get an Asthma Specialist for his condition, instead of just a Pediatrician, to monitor your son. That is what I do.
All the best,
Susan