You would need to have the doc write a formal letter (likely at further cost unfortunately) to reiterate that it was for a brief illness and has never in fact had any issues with asthma like symptoms before or since, as well as have your son (not you) send in an appeal letter with it. Problem is sometimes the blinders go on, they assume it is asthma triggered by viral symptoms (a real issue). They may double down and ask for respiratory medicine referral for an irritant challenge to prove without a doubt they do not have asthma. Went through this with my eldest...it got to the point that, with 3 negative irritant challenges, they were still saying no, that I suggested he politely word a letter saying what I was going to bluntly suggest that (a) the general duty medical officer actually read and acknowledge the respiratory medicine opinions and if they chose not to, (b) they would be getting a WTF letter from the Minister +/- the Surgeon General (friend of a friend) and the Chief of the Defence Staff (ex-boss). It should not get that far with your boy if all is actually as you state...they sometimes need more information and prodding.
