okay, i'm not a professional but my advice would be to do some very deep breathing like inhale as much as you can, hold it for a few seconds, then blow out slowly. yoga and meditation are very good ways to alleviate stress and calm yourself down. there is some controversey about kava kava, but this herb has a calming effect on your nervous system. i would consult a doctor first or do your own research first. don't do high impact cardio, go for a nice pace walk, and buy a yoga and/or meditation video and learn how to cope with it, and get some good breathing techniqes which is very soothing to the nervous system. when you get anxious about something, keep breathing. i hope this helps, however it sounds like you may have a slight case of anxiety or panic attacks and just knowing that your heart is doing that probably makes your case worse. just calm down and remember your mind is a powerful tool in assisting you through stress even illness at times. try to learn how to use it. i'm still learning, but i know it works. i used to worry alot, now i'm 28 years old and have learned alot so far through my journey. you will too if you put effort into it. try to find out more about alternative medicine, homeopathy, stuff like that! if you want to go the conventional way, you can learn on your own in the meantime. hope this helps!