elbow pain neg mri

my daughter was grabbed violently by a large woman who dragged her 40 feet. she was grabbed with the person's thumb on the inside of my daughter's elbow (front arm) the mri and xray show no tears or injury. my daughter is in pain, her right arm makes a popping sound every time she extends her arm it is very loud sound. she cannot lift heavy items and is in pain alot. she states she can feel "something" move against her bone (i think it is her tendon) she was diagnosed intially with a severs contusion and now with Lateral Epicondylitis but it is interesting that she is diagnosed with a repeatative movement diagnosis when she does not use the arm that was pulled. her injury is in her right arm and she is left handed. she was twisted and pulled elbow and shoulder. how can she be in pain when there is nothing showing up on the mri or xray? what should we be looking for? what is wrong with her??? please advise, I can send any additional information you may need.