I was using the band from the P90X and had it attached to a portable hook attached to a door. I guess that I applied too much body weight and it broke off and hit me right in the sternum. It's swollen now and I have a small cut. It hurts to breathe in and hurts to touch. I can't even apply ice on it. Just barely touching it, kills me. Do you think it's just bruised or should I go to the ER?