Heart Beatin Problem?

For about 3 months now my heart has been beating faster then it normally dose, For example when im relaxin it beats just has much as if i was ridin a bike or running. I notice mainly when im tryin to get to sleep. My girlfirend somtime can feel the power of the beat of my heart vibrate on the bed. Its mad. I have been eatin alot of junk food but cut down, And its still the same.. Any thoughts on this? I will eventally go to the doctors if it carrys on.