Hi. I am hoping that someone will be able to help me as I am feeling really desperate for answers. I am a 28 year old female and have been healthy my whole life. However, approximately 4 weeks ago, I began to experience episodes where my heart rate increases. These episodes happen randomly and infrequently. Some are minor where I just feel my heart rate increase but some are more significant where it gets to the point that I have trouble breathing, my whole body shakes, and I begin to sweat. These episodes can last just a few minutes or have been known to last hours (even up to 4 or 5 hours). I have no significant medical history and have been fortunate to be a healthy individual. I have been on the same birth control for a few years now with no issues. From April till August 2013, I exercised approximately 2-3 times per week before I endured an accidental hit to my face and broke my vomer bone in my nose. I have a severe deviated septum and have very limited breathing in my left nostril as a result. I have not had surgery yet to correct it. I do have a history of recurrent strep for which I always take Zithromax because I am allergic to many other antibiotics. However, I have not had to take Zithromax in approximately 6 months. After experiencing a severe episode in my primary care's office last week, I was rushed to the Emergency Department for further testing. All of my blood tests, CAT scans, and X-rays were normal, with the exception of slightly low potassium levels. I was placed on a 24 hour halter monitor. Although I did not experience any major episodes while wearing the halter, the cardiologist reported that my heart rhythm is normal but my pulse reached 140 while I was at rest. He has diagnosed me with Sinus Tachycardia. After following up with the cardiologist today, he is recommending that I begin to exercise again daily and that I begin to take a Beta blocker medication, on an as needed basis, when I have severe episodes. He said if this does not help in the next 2 weeks that he will have me wear a 10 day monitor and conduct more testing. My doctor was unable to explain to me why this is suddenly happening as well as what the appropriate treatment for this is. He explained that this is something that usually just goes away on its own but what is most concerning is that it is truly impeding on my quality of life and my ability to work. I am also not too keen on just taking medication to make a condition better without even understanding the etiology as well as having the course of treatment being so vague. If anyone could provide any suggestions, I would greatly appreciate it! Thank you!