They're called palputations . My mum gets them really badly because of stress
I get them occasionally beause of stress, and it can be caused by hormones at my age (16) .
My advice would be just go to the doctor and they will assess you based on your health record , take a blood sample and do an ECG (electrocardiogram) . All that means is they stick stickers all oer you , ask you to lie still and then this machine prints your heart pattern out .
If they arent 100% happy with that they might want to do a 24hr ECG ..the same but you carry a little box round round your waist .
Its nothing to worry about :D xx