Dear Lucy,
Although I can’t be sure without examining you, this sounds like a common problem that many adolescents have. The heart beating fast may be caused by not having enough fluid in your tank. Even if you are not thirsty, you are may be running yourself a bit dry. What I recommend is that you have four 8-12 ounce glasses of fluid a day and a salty snack (pretzels, saltines, pickles). Also, you should not skip meals and you should totally eliminate caffeine. This tends to help the large majority of patients whom I see with these problems. If this does not go away despite these interventions, or you have other symptoms, you should see your primary care provider for more evaluation. They may want to perform an electrocardiogram as a baseline test, and consider longer ECG monitoring. As well, you may want to count how many heartbeats you are having in one minute’s time; if it is 180, or more, at rest, this may be indicative of an arrhythmia.
I normally drink alot of water each day since its a habit my mother taught me when i was younger. although I do not always take salty snacks so i'll start with that. I usually make sure I eat whenever i'm hungry. I do not take caffeine since I don't like thing like coffee and etc. So I will try this out and then if its not working out I would seek primary care. Thanks you for helping me out.
~ Lucy