Answer :
A panic attack. I've experienced them and they are not fun at all. They can either be triggered by something seemingly small or even nothing at all. If you are having a panic attack, while it's preferable not to have to go to the hospital, it's better to get checked out and find out that it's a panic attack than to not go and find out it's a heart attack. While it may not be what you think it is, the symptoms are real, and should be treated as such. There is no reason to feel guilty for being concerned with your health.