This is Dr. David
how fast is your pulse rate?
have you had your thyroid hormone levels checked?
have you had an ECG of your heart?
fast heart rate at risk could be atrial fibrillation, or high thyroid hormone levels.
you need to see your doctor and get an ECG heart tracing study and blood testing to check your thyroid hormone levels.
these are the first tests you need to have done, and after that you might need more testing.
do you have a doctor you can see to check your heart out and run some blood tests?