I don't often post in this forum, but I wanted to give you some encouragement and offer some advice, as I too have MVP. Mine is caused by lupus. Inflammation of my mitral valve. When I first started noticing the symptoms of a racing heart, palpitations, etc, it scared the crap out of me. I also, thought my heart was going to leap forth and exit my body.
When my lupus diagnosis came, along with the MVP and a bunch of other stuff, they put me on prednisone. It killed the inflammation and the palpitations, racing, etc, disappeared within a few days! Is your MVP caused by inflammation?
Do you suffer from anxiety? That can cause these symptoms. You mentioned some symptoms like shivers, you feel you're going nuts (who wouldn't if this is happening), racing heart, palpitations, etc. Those can be anxiety related too. Do you feel "ramped up"? Almost hyper? I have anxiety, so I know the symptoms!
Also, have you checked your blood pressure recently? You might want to get that checked.... I'm having some new issues with high blood pressure. Never had it before, and we don't know why I do now. But my systolic number (when the heart is puping the blood through) is normal. But my dystolic number (when the heart is at rest, not pumping), is high. I'm mentioning this because you said you noticed the symptoms when you're just sitting or talking or watching t.v. That's when I notice my symptoms too. When I'm "relaxed".
How do you feel after you exercise? Do you get dizzy and feel sick? Any problems exercising?
I'm just thinking out loud on some of this for you. I do "get" what you're saying. I know there are lots here who have MVP as well. The more info you can get the better. I hope the answers come quickly for you!
All the best,