My father is 63yrs old. He has been a runner all his life, but I noticed his performance has dramatically worsened over the last year. Just last year he ran circles around me, but now this year when he came to visit me at Christmas he was far slower than I have ever seen, I had to wait for him several times on a 3mi run to catch up. He called me last week and told me that he had a sudden bout of extreme sweating, fatigue, nausea, and lightheadedness.