The first doctor’s suggestion of the diagnosis of Hyperventilation, in the face of “tingling on my hands and arms”, is reasonable but the recurrent shortness of breath is worrisome and you should be reevaluated for other causes
of shortness of breath, some more serious, most notably recurrent blood clots to the lungs (pulmonary emboli) .
You also mention that your “heart was racing” yesterday, on your way to the train.