There could be several causes
of the symptoms you are having.
Do you have any associated features of reflux, nausea, vomiting, change in bowel habits, etc?
Do you take alcohol? Are you on any medication?
Do you remember any history of trauma or injury to the site?
You would need to rule out GERD, gastritis, duodenal ulcers, chronic pancreatitis, etc.
Have any investigations been done as yet? Is there any releif with pain relief medications or antireflux medications?