most likely anxiety attack.
by your avatar, i take it you are a woman. based on your statement, i take it you are not really old (still menstruating). young woman who has no known heart disease
are very unlikely to have heart problem. unless you are a smoker, use birth control, have diabetes
, have high blood pressure
, and have family member who had heart attack
at young age, i would not worry about it much. in fact, i would stop worrying so much, which is probably your problem.
having said all that, if you are that concerned, go see a doctor, do a stress test
. i would be more inclined to seek help if your symptoms get worse when you exercise (run, lift heavy weights, go up the stairs, etc).