Ever considered....?

Have you ever had your heart checked? I used to think I was just out of shape -even as a teenager I was thin but had a hard time with exercise- but it turned out to be a common valve problem called mitral valve prolapse. It wasn't even known to exist until the 1970's, when technology allowed watching the heart's actions in real time.

Off the top of my head, some of the symptoms are shortness of breath and exercise intolerance, but also a thin physique with long fingers (!) and often waking in the middle of the night with unexplained shortness of breath.

The connective tissue disorder site (ctds.com) attributes it to magnesium and hyaluronic acid deficiency.