Okay, well at least you have checked out medically...that is good news.:)
Now you will want and need to find a doctor who knows how to help treat a patient with anxiety...or perhaps give a therapy referral!
Until then, I am going to post a link that has two url's for breathing exercises (from our Resource Guide) as well as directions for 'The Divided Breath'...my personal favorite anxiety reducer. When I had the shortness of breath symptom, it worked for me when nothing else did.:)
https://www.healingwell.com/community/default.aspx?f=9&m=2064222
I wish you the best...give these a try and see how you do. Also look into seeing a doctor that will take you seriously and partner with you through this struggle.
S.C.