Sounds like tachycardia to me. I just had one of those episodes myself a few weeks ago, scary huh? They can be brought on my many different things. Caffiene, low blood sugar level(hypoglycemia)stress, anxiety. I use to get them alot as a young girl and when I hit my 30's they got less frequent and in the 40's even less, but I just had a couple spells. I also have mitral valve prolapse and recently hypoglycemia(which brought on the last episode, working out and then grabbing a StarBucks coffee and scone just put it all into action, took 3 hrs to get mine down. Majority of the time these are benign incedents, but one thing is, WE are NEVER too young for heart problems in this day and age, and he shouldn't have poo pooed you off like that. You must be female by his reaction. Never take us serious. Either sex he shouldn't have side kicked your symptoms.