Hello,
Shortness of breath and tiredness are symptomatic of anemia. Even vitamin D deficiency can cause extreme tiredness. I suggest you to get an evaluation done and a complete blood profile for anemia done to determine the type and start with the treatment.
It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your doctor. I sincerely hope that helps. Take care and please do keep me posted on how you are doing.
Did he listen to your lungs? or have you do any sort of test to test for lung strength/obstruction? How's your blood pressure and such? I would go in and mention the shortness as breath as a primary symptom. Have them test again for anemia because I'm almost willing to bet that the respiratory distress is causing the fatigue at this point.