You may not like of what I may say, go to a cardologist and get a heart checkup, this is not to make you scared, just to make sure you are doing ok. You are 55 years, right in the age group prone to heart attacks ot strokes. You are a bit active, 2 to 3 times a week. You need a complete physical as well to check to high blood pressure and diabetes. It never hurts to check everything possible to eliminate the impossible. Never hurts to check things out to make sure everything is fine. You let us know how you are doing. Hugs for today.