Hay fever or asthma ?

I train regularly on a swim team at several different pools. Lately, while I have been training at one of the pools, I have been getting a severe cough during practice. I don't understand what it is but I don't think it is my asthma, since taking my inhaler doesn't help and my peak flow meter stays up throughout the practice. I have been getting this cough ever since the pool re-opened from construction. Could I be coughing because I am allergic to something that was used during the construction? I don't cough when I swim at any of the other pools I train at. Could I be coughing because it is an indoor pool instead of an outdoor one? I really don't understand it and neither does my asthma pulmonologist.

I have also noticed that this cough only occurs when I am stressing my lungs. It takes a while for my cough to get really severe (like I get it about an hour into practice) and it will slowly go away if I get out of the water and sit or just take it easy for a while. Please help!