Bullet in the back?

So it started like this: I had back pain at one point on one side, and now I can feel a ball there. It's hard and located to the right of the spine and under the ribs. Later I could feel it on the other side too, but a little displaced, so not at the same level. The back pain is gone now, though. I also have a cough where I cough, then can't breathe, cough again, and feel a gag reflex, and this happens 1-3 times in a row. But I only cough about twice a day. What could it be?