I may be getting into trouble here, since I’ve only gotten as far as the OP, but —
GO SEE A DOCTOR WITH EXPERTISE IN ASTHMA!
That’s an allergist, or a pulmonologist. You don’t need to breathe differently, you don’t need to eat or drank some substance, or avoid some substance. What you need to do is GET YOUR ASTHMA PROPERLY TREATED.
You may need to take daily medication either for awhile or long term. You may need to medicate just prior to exercising. Regardless, you need medicine. Yes, it’s a pain in the backside but so is not being able to breathe. Get this properly taken care of you will no longer have this sort of “I can’t breathe” problem when trying to exercise. Failing to treat this can leave you open to all sorts of really unpleasant, nasty complications. No to frighten you, but asthma can kill. Get this taken care of.
The other possibility here is that you don’t have asthma, but some other lung disease. Well, you’d still need to get that treated, anyhow. Bottom line - you need to see a competant doctor with some knowledge/expertise in this area.