First of all try to stay calm.
The fact that you can actually feel your heart beating really fast indicates that you are having palpitations. I would advise you to get a couple of tests done like hemoglobin
function test, blood sugar levels, ECG to rule out other causes of palpitations.. If the test results come back as normal , feel reassured that nothing is wrong with you, it must be a simple case of anxiety
Exercise will really help. Even if you feel it is difficult to step out of the house to get a work out, you can always get an aerobics
workout DVD and do it at home.
Another thing that will help is yoga/ relaxation exercises. Sign up for yoga/relaxation classes.
Drink at least 8-10 glasses of water a day.
Hope this helps.
Dr. Divya Kuttikrishnan