i've been experiencing blacking out when standing up which lasts for about 10 seconds. One time, I lost control and fell down. My heartbeat races so fast and have a hard time breathing. I've been experiencing this since i was like 7 or 8 and now i'm 13. Does this have nything related to the heart of anxiety? Because, 3 weeks ago, i experieced chest pain (mostly left and sometimes right) pinching and burning pain. I also keep on waking up catching my breath and rapid heartbeat. Is this most likely anxiety? I've been experiencing light and heavy headaches atleast everyday. My hands and feet shake a lot for.no reason but somtimes because i'm nervous. I'm actually worried because I experience black out literally everytime i stand up.