unknown continues chest pain even after heart bypass surgery

A diabetic , hypertensive patient since last 10 year.
A CABG operated heart patient from “Usha Mullapudi Cardiac Hospital Hyderabad in Aug 2007(almost 3 year past )
Later on PTCA stenting (angioplasty)in Aug 2008.
Suture removal in july 2010. (steel wires drawn out from sternum bone which were put after CABG operation in 2007.)
Patient problem:
An unknown continuous pain 24 hrs near operated chest and near suture area of chest bone since after operation.
Patient has conveyed the problem to the cardiologists/cardio surgeons but they say that for few persons after operation it takes longer time to calm down the pain, and suggest to take pain killer if pain continues.
Patient has been checked up by various tests depicted below for any heart related problem, regularly after heart operation. Test report answers every checkup to be good, under normal conditions .Doctors say it’s not heart pain but may be a muscular pain or something other than cardiac pain. And is un ansrable.

Medical checkup:(done regularly at every 6 months)
Patient has been checked up by:
1.Angiography
2.ECG (electro  cardio graph)
3. TMT(tread Mill test)
4.Radiology
5.X-ray
6.Stress eco test.
And the every results/reports are all normal/ok.
But still a ? for pain reason.
But no one is able to pick up his problem.
The patient walks freely, but carries a unknown pain with him where ever he visits. Sometimes he starts crying for his pain.He thinks to quit his life.
Every 24 hrs patients mind is sticked to his unknown pain sir.He makes guess that -is something left inside his body after the operation.
What to do and What not to do…..?
Help me sir….

Request:
Sir can you please suggest the pain reason.
And give your valuable opinion for the cause of pain to patient.