Since May of this year I've been periodically woken with rapid heartbeat and labored breathing, my left arm at the shoulder to elbow aches, during the day my heart will start beating like crazy and I will get out of breath, my chest has started aching as well. I also sometimes feel like I have heartburn or something is in the back of my throat. This is progressively getting worse, which is no good since I have a very physical job. I've had an EKG and an echo, both of which were apparently negative, I am currently wearing a week-long event monitor. Basically my doc has blown me off since the echo came back negative, I would like to know at least what it could be. Should I get a second opinion? Thanks.