What Could Be The Reason For Sharp Pain In Armpit Towards Right Breast?

Last week i fell on my chest while holding a couple of plastic bottles of soda water. I had chest pains but no bruising. I did have a chest xray and no fructures were visible . But 7 days after i still have sharp pain just below my armpit and towards the side of my right breast. I have trouble sleeping at tonight because it is particularly painful to turn in bed and to sleep on my side. What could have i done to experience this continued pain. What should i be doing to recover.