I've been dealing with upper abdominal pain that radiates from my sternum

I've been dealing with upper abdominal pain that radiates from my sternum to the right side and between my shoulder blades and upper right shoulder. The pain seems to subside in the morning but gets progressively worse throughout the day. It's accompanied by nausea and loss of appetite. I have had several ct scans HIDA scans and ultrasounds and X-rays. The Drs (I'm on my fourth) say they have no idea what it is. I have been to the ER several times with no results. This has been going on for almost two years now and is getting worse by the day. I sometimes freak out because I think it's something serious but have faith that if it were the labs and scans would have identified it. It also causes bouts of daily heart burn. I have tried all the usual drugs. I am at my wits end and quite frankly can't take it anymore. Any suggestions would be appreciated.