I am 51 YO. Been running for 41 years. Was in very good shape. For last 4 months have been steadily declining in running performance from 10 miles to now labored walking. Have had many episodes of intense chest pain, labored breathing, neck and back pain, distorted vision. Have had EKG, stress test, and echocardiogram. All ok. Started using inhaler, helps a little, but episodes continue.