What are otjer reasons for chest pain?

I was having chest pain Sunday 5/29. I went to the ER and had blood taken, and they did an ekg and xrays. I was told that since I am 27 and early heart attacks do not run in my family that more than likely its not a cardiac issue. The ER doctor said everything looked fine and I wad released. I do suffer from acid reflux and take medication. I continue to have these pains in my chest along with discomfort in my left ARM. Any other ideas as to what It may be?