Pancreatitis is inflammation of pancreas which can be acute or chronic.Gall stones form the second major cause for this.It can be presumed that you had gall stones as you have already undergone removal of gall bladder.But,history wise your symptoms do not match well.The pain of pancreatitis is usually in the central part of upper abdomen and radiates to the back.To confirm you can undergo further investigations in the form of S.Lipase,S.amylase,USG abdomen,ERCP etc.Lupus is an autoimmune condition that can also be detected by blood tests.Of all the conditions that have been mentioned by you,those mentioned by your doctor seem the most probable.Gastroparesis or intestinal adhesions may be another cause.IBD is more associated with type A personality and is diagnosis of exclusion.There is no need for your fears ,you can just accept what your doctor has said,stop thinking too much about it and get on with life.