I Have Been Having A Quivering Sensation In My Chest.

I have been having a quivering sensation in my chest. It lasts about 30 seconds. I have no other symptoms, no fever, no pain down my neck or arms, no nausea. I do have a lot of burping when this occurs but I don't know if it is related. It only happens at night when I am sleeping. I am not anxious before it happens but I get anxious afterwards. I can feel my pulse beating regularly under the quivering, maybe my pulse is a little faster than normal but not extremely.