I am having difficulty doing treadmill workouts, get dizzy, faint,SOB. chestpain. Also happens climbing stairs and I feel like I am going to faint or pass out, usually have chest pain or discomfort with is. I am 65 yr. old woman, was in good health until this started . Have had numerous heart test, all negative, except 24 hour monitor, show arryhmia in my heart, extra heart beats