It could be just harmless palpitations (Google PVCs). But I would call the doctor and get checked out just in case. If it continues go to the emergency room and they will do all the tests to make sure it's nothing serious. Good Luck!
This sounds like a panic attack and I say this because it sounds a lot like the ones I've had in the past. It's quite scary to have happen. At times my left arm would go numb even. Almost 2 years later and after having ultrasounds on my heart and being told it's perfectly healthy I have finally realized it is anxiety. Doc put me on blood pressure meds and prozac to control it and I almost feel normal again. I am about ten years older than you but anxiety can hit you at any time in life, especially if you are going through stressful situations. It could be something else though so you should definitely see your doctor right away so they can evaluate you. I hope the best for you, keep us updated.