Sob. Chest xray ok. Echo - some damage. Stress test/nuclear- heart skips every other beat; right ventricle enlrgd. Oxygen ok. No hbp. Why sob? Next?

Short of breath . Ct scan of the chest. If your right ventricle is enlarged and you have shortness of breath further testing is indicated. Causes such as pulmonary embolism, pulmonary hypertension, interstitial lung disease, vasculitis need to be considered. You should probably see a pulmonologist.
Cardiac . There is not enough information here to advise you specifically. You should discuss your status with your doctor and ask to be made to understand your problem and status.