Shortness Of Breath When Riding Spin Cycle. History Of Sagging Mitral Valve. Possibility Of Cardiac, Pulmonary Problem?

I have shortness of breath when riding a spin cycle, which I have been doing for 4 months, and never had this feeling before. It feels like I cannot get a deep breath. Also, last night I woke up feeling like I could not inhale. I have been diagnosed with a sagging mitral valve , but not a defined prolapse , many years ago. Can any ofmthis be either cardiac or pulmonary problems. My son has Marphans Syndrome, and we do ot know which side of the family he inherited it from. Julie Atteberry