No personal experience with Asthma. But, you write like you're searching and I have heard of one thing I would thoroughly check out if I were faced with that challenge. (I like to understand the principals behind a thing and this sounds like it has merit to me.)
First heard of it in a book about a Pakistani doctor that was thrown in a political prison and went on to help the other prisoners with their medical issues. Had no medicines available and so water and it's liberal use was what he had to proscribe. Asthma was one of the many things he felt abundant drinking of water would cure.
You know that when you breath out moisture is expelled from your lungs. (Fogging a mirror.) This adds up to some amount like a pint per day. So, under this line of thinking an 'asthma attack' would be the body triggered by indications of dehydration. The lungs close down as one more way to conserve a scarce resource. The solution would be abundant hydration. (Think I remember one to one and a half gallons per day for a person in rather sedentary conditions.
Seems simple and harmless enough to run a test on.
Welcome to The House by the way.
