What Causes Pain Near Breast And Neck?

I have had pain on my left side near my breast .Sometimes it feels like the pain moves down my side and sometimes in my neck.I have had an MRI of my upper and lower abdominal.I have had a synagram of my neck and had a mammogram.Have had a ekg and stress test and my blood checked.I am in pain what could this be.I was a server for 26 years and carried heavy tray on my left side could this be the problem.Please help!