I've had palpitations for years. They started when I was in my twenties and now I'm almost 50. I've had EKGs, also a stress test
with an ultrasound
which were normal.
Palpitations are more common in women. I agree, they are kind of scary. The usual causes though are too much caffeine, lack of sleep, stress, taking stimulants, or eating red meat. Usually the palpitation is an extra beat in your heart rhythm.
Try getting extra rest, cut down on caffeine and see if that helps.