Have Heart Murmur, Exhaust During Exercise, Feel The Pulse, Acute Pain In Chest On Breathing. Cure?

I have a heart murmur , 29, and just have a few questions concerning it. I find aerobic exercises to be extremely exhausting, no matter the level of intensity or length of time. When performing, I m a trumpet player, as I get nervous I feel my heart beating abnormally hard and loud; I can feel it pulse nearly through my entire body. My energy levels fluctuate daily, and at times will have these acute pains in my chest when I breathe in. I am overweight but stay fairly active exercising roughly 4 times a week. Diet consists of mainly proteins and small carbs, typically a white/brown rice mixture. My main concern is that as my diet is improving, will a heart murmur limit me in terms of physical activity, or is that due to something else? During exercises I feel as if my body isn t getting enough oxygen or proper blood flow .