Palpitations are feelings or sensations that your heart is pounding or racing. They can be felt in your chest, throat, or neck. You may Have an unpleasant awareness of your own heartbeat or may Feel like your heart skipped or stopped beats The heart's rhythm may be normal or abnormal when you have palpitations. Normally the heart beats 60 to 100 times per minute. The rate may drop below 60 beats per minute in people who exercise routinely or take medicines that slow the heart. If your heart rate is fast (over 100 beats per minute), this is called tachycardia. A heart rate slower than 60 is called bradycardia. An occasional extra heartbeat is known as extrasystole. Palpitations are not serious most of the time. Sensations representing an abnormal heart rhythm (arrhythmia) may be more serious. In your case if your periods are long and having profuse bleeding you can have anaemia which can increase your palpitation and also can cause shortness of breath. To check for that you can get your hemoglobin level done And you can get back to me with the reports for a proper consultation