first of all, i don't think you have any heart problem. the signs of heart problem are rarely faster heart beat!! I am a medical student and had anxiety myself, now am older and healthy. I laugh when i remeber that. I felt exactly are feeling....i would dial the 911 thinking i was going to have a heart attack, or brain cancer,, generally i felt something was wrong...i was scared of doctors, reading about the heart problems, ....so many things!I even lost track of reality..felt confused, etc
eventually, i realized two years had passed and i wasn't dead yet, and I did not have any heart attack, so I saw a doctor!after an ECG, EEG. he told me i had anxiety! After couselling and some drugs it was completely gone.
anxiety is a common problem, your heart paces when you get scared or anxious. this an adrenaline rush, usually, this is not bad but it can make you really uncomfortable....and affect how you eat, your social life, which sucks! but dont worry about it much, it's not dangerous, unless you have high blood pressure or other complications already.
by the way, most people with anxiety tend to feel as if they are having heart attacks, lack of breath, feel pain in the chest and ribs, faint, heart pacing, or sometimes they listen to the heart and think its gonna stop....this is just adrenaline effect.
sometimes people with aniety feel as though the heart has really stopped beating and they slowly dying, mixed with the faint feeling.....this can scare the hell out you!
the truth is there absolutely nothing wrong with the heart, infact the heart is doing it's job when it goes faster during the anxiety....meaning it's healthy- eventually it goes back to normal when you relax!!
anxiety is caused by chemical imbalace in your body, which is easily treated.
please see a doctor soon, don't be scared at all.....I assume you are young!!! most young people DO NOT have heart problems....if you had a heart problem, trust me....everyone would know. this is because heart problems have severe symptoms!!
exercising also makes your heart pace faster, which is normal, now when you have the anxiety....you feel as if the heart is running out of the chest. do not get scared, your body is made such that it will counteract this. Just have a sit and relax for a while until you feel better.
caffeine stimulates your body, makes you alert. it is thus not good to take caffeine, because you can't really relax.
one more thing, adrenaline is more during the times , approxiamtely 10pm at night to 10am in the morning(when you are about to sleep and after you wake up) this is normal.therefore people often feel anxious in the evening or in the morning.
stress can also increase anxiety. stress can be managed by drugs, but you very young. When you get older stress goes away....in most cases.
That's it, so see a doctor and get to your fitness soon, I HOPE THAT I DIDN'T SCARE YOU. take care buddy!