Heart/Chest Pains happens when laying in bed or sitting/

I am in my early 20s and sometimes during the year I get these horrible pains in my heart/chest. Last time it happened I was sitting on the couch in a strange position, my back was very arched. And when I got up the pain began and I had to lay down on my chest and refrain from moving too much. It goes away after some time. It usually happens when I am laying in bed or sitting strange. Is this anything I should look into to? Does anyone else have this problem?