Suggest Treatment For Heart Beating Fast

So i went to the hospital at about 2-3 in the morning yesterday because i felt like my heart was beating to fast. It seemed like it was getting to be to much, plus i was frightened at what was happening. The only thing that i think it could have been was a caffeine overdose, since i had chugged a medium size black coffee from starbucks before attending the midnight premiere where i was at when this started. I had my heart checked out and everything. Everything was healthy. I was told to eat something, drink water, and sleep. Well i did that, i fell asleep at 4 and woke up at 8, feeling resltess i ran on the eliptical. I then fell back asleep untill 11. Now for the past two days my chest feels... almost indescribable. My heart rate keeps rising, almost like i'm panicing, Which is [art of it because i don't know whats happening and i want his to go away. My chest just feels... tight and sort of fluttery. I went into the hospital again and was told i'm fine, i'm just amping myself up, but it starts instantly every time i wake up..... Some other symptoms, i'm exhausted, shaky at times, lack of appetite, threw up/dry heaved yesterday. I'm just kind of scared and i need some answers.