What Causes Pulling Sensation In Armpit Upon Movement?

Underneath my left armpit, for the past couple day it felt slightly swollen. Last night as I pushed a dinning chair back in, I fell like a snap/pull underneath my armpit. It didn't hurt was just uncomfortable. For the rest of the night if I would move my arm in a certian way, I could feel the same snapping/pulling in the same place. I guess the best way to describe the location is on the upper portion of my arm pit towards by back. Is this something I should be concerned about and how do I get the feeling to go away?