Hello, My Name Is Kim And Last Week I Slipped

hello, my name is kim and last week i slipped on the stairs at work. i broke my fall by grabbing on to the railing and by doing so felt something pull in my upper chest. went to dr and got xrays there was nothing there and they said i pulled chest muscles. i am in extreme pain all the way around my chest to the back. it does not seem to be easing at all. my main concern is that 1 yr. ago i was in a car accident and received a fractured sternum. what can i do for this pain and could i have re injured my sternum?