Asthma?

I would guess it's a positioning thing. Maybe your bike fitters can work with you to lessen that.  You probably won't be as aero, but I tend to think being able to breathe is more important. 

If it's noticably worse in aero, then no doubt your position is a contributing factor. But I think there's something about biking itself that makes asthma worse. Mine is allergy-induced, and the attacks are usually delayed until several hours later, often at night. Almost invariably I have them after biking, whether here in Vietnam or in the US, unless I take preventative meds. I also tend to get congested, runny nose, itchy eyes, etc. while riding. I rarely have such problems during or after running, unless I'm sick or pollution levels are very high. I'm guessing that on the bike I'm in closer proximity to pollution from traffic, and going faster so inhaling more other triggers, such as pollen, smoke, dust, etc. than when running.

My bike buddy used to joke that I must be "allergic to biking"--it's not too far from the truth!

 double post--Internet is wonky here tonight as an undersea cable is down..

That's great!  I might start taking it again.  I stopped because we couldn't afford it.

i went from ~$200 per month to $400 to fill a 3-month scrip!  YAY!