You're having an anxiety attack, or let me say, it sounds like that's what's happening given you've had your heart tested a lot and nothing has been found. You're also posting on an anxiety forum, so I'm guessing you know this. So let me ask, what are you doing as far as treatment for your anxiety? Are you in therapy? Learning any relaxation techniques? Do you have people you can talk to when you feel like this? A long time ago I read an interesting comment from an anxiety therapist that said, okay, you're having an anxiety attack, put your feet up and relax, it'll go away. Now, I'm not someone who actually believes that now or believed it then, it's really hard to do when you're in the middle of an anxiety attack, but it does give you a way of looking at it. So again, as it appears you don't have a heart problem, you need a different approach, and so, what have you done to seek help for your anxiety?