The views expressed by me are for educational purposes only and do not establish a doctor patient relationship.
I am Mysticdoc, experienced Internal Medicine Specialist.
I am here to help you with your concerns.
Sorry to hear that.
There can be some other possibilities.
Neurological conditions can cause weakness of the breathing muscles and the diaphragm.
Phrenic nerve palsy is one such condition.
Also Myesthenia gravis can cause the respiratory muscle weakness.
Hence a consultation with a neurologist will be appropriate.
Also di you get any heart test done like echocardiogram, stress test?
If you did not, then these tests should be considered as well to rule out any heart failure.
Also, pulmonary embolism or blood clot in the lungs is another condition that should be ruled out with a CT scan with contrast or pulmonary angiogram.