Finally, (after a myriad of tests) the pulmonologist agreed that my shortness of breath was a muscle weakness in the chest wall possibly due to MS and he prescribes a device to exercise and improve these muscles ($25). pnmedical.com/the-breather/
I encourage anyone with shortness of breath to assure there are no other underlying cardio-pulmonary problems but if none are found, realize that with even mild-moderate MS the muscles of breathing can become weak (as with arms, legs etc.) and need to be exercised or will become weaker.
Hope this "PSA" helps someone else