Burning Below Rib Cage - Right Side - Any Ideas?

Hello there.....  I have had this off and on for about 3 years now.  It went away for about 2 years but just came back with a vengence.  Basically on the right side of my body below the rib cage within about a 2 to 4 inch diameter there is a burning feeling.  It comes off and on throughout the day, all day but fine when I sleep.  Its more annoying than anything and not terribly painful and I have NO pain in my back or anything at all.  I noticed when I drank caffine that it felt a bit worse.  I am not sure if its gastric, liver, or an ulcer.  Any ideas by any chance?  Thank you so much!