Stomach "Angina"

Had triple bypass May 2002, and for the last 3 months have had pretty bad pains in my lower stomach/gut area. Various tests, scans & procedures later my gastro doctor thinks it may be stomach problems or more worryingly angina of the stomach area. Seemingly this pain is caused by narrowing of the vessels to/from the stomach similar to heart angina. Has anyone heard of this or came across this condition. It is worrying me quite badly again. I am in daily pain and after 3 months getting pretty fed up with things again.