Let me throw something out here just for the heck of it...
Shortly after our son was born, I began having heart palpitations like I hadn't had since I was a teenager. Never did anything about them at that time (I just assumed they were normal) but was very concerned now so I told my doctor. After many tests, I was diagnosed with Mitral Valve Prolapse with Atrial Fib and put on beta blockers which seemed to resolve the problem. I still take beta blockers many, many, years later.
Anyway, I was one proud daddy and, just as soon as our son was old enough (hold his head up on his own, etc.) I would carry him around up on my shoulders. I would stand facing his back, put my hands under his arms, and lift him over my head and onto my shoulders. At the mall, in the grocery store, at the park when he was tired of walking/playing - he would be up on my shoulders.
I don't know exactly when it began, but one day a year or so after I started the beta blockers, I had a terrible pain in the center of my chest. I thought for sure I was having a heart attack, went to the ER and everything, but they told me I checked out fine. Said maybe just stress.
So, these pains would come on pretty regular; a couple of times a month, anyway, and would last for hours. I would usually "sleep it off" and wake up feeling better the next day. Then came the day that I suddenly understood what was happening -
It was the lifting my son over my shoulders thing!
As he got older and heavier, lifting him over my head was apparently putting a lot of stress on the point where my chest muscles / ribs attach to the sternum (the bone running down the center of the rib cage). I wouldn't feel the pain immediately, but always a few hours later. And the pain would always last for hours, then go away until the next time we went to the mall, the grocery store, or the park.
