Palpitations is a generalized term. Are you experiencing an increased heart rate or are they perceived as skipped beats? Have you sought medical evaluation since the onset of these symptoms? If so, what was the diagnosis? Also, do you have any underlying cardiovascular issues that you are aware of?
Since you were advised to disregard the palpitations I can assume the physician diagnosed you with benign premature ventricular or atrial contractions. While it is true that these extra heartbeats are generally considered benign in individuals without underlying heart disease, I feel it is time for your cardiovascular health to be reevaluated. The fact that these palpitations were accompanied by shortness of breath, chest discomfort and pre-syncope, suggests that you need to be evaluated for ischemic heart disease. I feel that it would be a prudent measure to make an appointment with your primary care physician. There is a strong probability that he or she will schedule a stress test. If your condition worsens I advise you to promptly seek medical attention.