This patient support community is for discussions relating to asthma control, breathing difficulty, bronchodilators, children's asthma, drug allergies, exercise-induced asthma, house dust and indoor allergens, pets, school issues, and sports activity.
You could also try taking Benadryl and seeing if you can take a deep breath after 25 minutes. But the mask also covers irritants. Both are easy tests.
IF ALLERGY
Claritin probably isn't going to affect the mucus. Very similar but slightly different is Clarinex. Clarinex might slow down mucus if from allergy. You can also try a nebulizer with Sodium Cromolyn soultion. Works in 5 minutes but doesn't last more than a couple of hours. It will slow down the mucus cells that react to allergy.
My allergy is pretty bad from pollens including foods that I eat. But when I go out for exercise I wear a paper mask over my mouth. With a mask I can walk a 12 minute 1/4 mile. With out the mask I walk a 15 minute mile. So you can see how my allergies affect my times.
I'd start with a pulmonologist to clear lung problems or infection. After that might try an allergist.
I also have asthma that only happens when I reach a specific level of exercise and doesn't show otherwise besides allergy induced. Sorry to hear that you are having problems. I now what it feels like. :(