Approximately 4 Weeks Ago I Fell In My Bathroom; I

approximately 4 weeks ago I fell in my bathroom; I have had a knee replacement and therefore cannot use my knees to help me up. I put my right arm on the bathtub and used it to help me get up (330# of me). I really didn't have any other pain until one week after I fell. I had nonmanageable pain in my right shoulder into my armpit. I had it x-rayed but they found nothing. Put me on steroids and pain medication which helped immensely. I still have some shoulder pain but it is mostly around my collarbone and will go into my armpit. If I cross by left arm over to touch my right shoulder I can feel it under my arm which also happens occasionally when taking a deep breath. Today I can feel that there is a soft lump near my collarbone and now I'm obsessing about having breast cancer.....please help!