I haven't told anyone yet, but, I have been having slight issues with my heart and cardiovascular health. I am a bit worried because I am only barely sixteen years old, and if I am having heart troubles that could be a very bad sign in terms of my health. The last week or two I've noticed that a couple times a day, my heart feels real sore, and sometimes I feel like I cannot eat or drink anything because of it. The worst happened this morning when I woke up and my heart felt really sore and cold, and I had my hand on my chest for five minutes until it went away. I think that it may be connected with these breathing exercises I have been taking up lately to help me develop breath control since I do a lot of singing. Some of these including inhaling slowly while counting to a certain number in my head, and doing the same while I exhale, along with holding my breath and breathing in certain ways.