I am a female, 5 -2 , about 135 lb, and 65 years old. I just retired from 38 years of teaching at middle school. For the last 20+ years I have jogged 2 miles daily. But within the last month or so, I ve had to walk half of the way, getting exhausted. Other symptoms include stiffness in left arm, labored/shortnesss of breathing, overall muscle weakness, and a cough. Got any ideas ?