What Causes Persistent Pain In The Sternum?

My daughter was admitted to the hospital this past week with severe pain in the sternum area. No heart related issues were diagnosed. Based on lab results and CT scan they diagnosed ascending cholangitis. An ERCT procedure was performed. A narrowing of the bile duct was found and treated. The pain in the sternum subsided for one day, but each day thereafter the pain has become more intense. She is still hospitalized and they have put her on a self-administering pain killer. Lab work show her liver and other # s improving but are baffled by the pain. An MRI is scheduled for Sunday, 5/3/15. She is a 47 year old type 1 diabetic who bikes, runs and works out on a regular basis. She was diagnosed with lyme disease several years ago and was immediately treated.