If the phrenic nerve were damaged, changes would be seen on the chest x-ray and your pulmonary function tests (PFTs) wouldn
Shortness of breath associated with mild exertion suggests phrenic nerve involvement. But your pulmonary tests and chest X-rays appear to rule out diaphragmatic paralysis.
The use of a pulse-oximeter to record your blood-oxygen levels during the day would be helpful. These use-at-home instruments are somewhat expensive. But you might be able to obtain one for temporary use.
Also, an overnight sleep study is suggested to rule out sleep apnea as a contributor to day time fatigue. A use-at-home device is also available for this purpose.
The analysis of changes in blood-oxygen levels might help identify the specific conditions associated with shortness of breath.
i feel the same way. My doctor said it was allergies. I sometimes have allergies in the spring and fall but this is a definate starvation for air. I yawn also because I feel that is the only way to get a deep breat. I am getting a chest xray and blood work done but in the meqntime is there anything i can take to make me breath better.