Hi,
In for me to reply to you I would need more information about your medical history or at least an idea of what brings the difficulty of breathing.
Can be anxiety, asthma or a number of other reasons.
However I would highly recommend swing your primary care physician at this point.

If this is a chronic problem and you are not able to pin point the cause, then an allergist and pulmonologist are in your future. A pft test and allergy test are first steps to figuring it out.