I am 60 yrs old, BP of 110/70, 155lbs, non-smoker, supposedly in good health according to doc and physical exam and related test results. I have been diagnosed with mild MVP, for which my doc prescribed 25mg of Metaprolol to mask the symptoms. Each morning I excercise, alternate periods of 50 jumping jacks with, 75 push-offs, 75 leg lifts, and 75 toe-touches, and ending with 50 more jumping jacks. However, there are times that I do work around the house. Last year I got 12 40lb bags of fill dirt, and spread it in low spots around the foundation. Afterwards I started to feel awful - exhausted, weak, bloated feeling in stomach, a bit dizzy - like my heart wasn't able to pump enough blood, and a bit headachy. This feeling persisted for hours and didn't go away completley for 3 days. Sometimes this happens when I play tennis. While I am exerting myself, I can't tell when I "cross the line" into this phase. What is wrong with me? My doctor isn't helpful.