What Causes Heartburn And Burning Sensation In Upper Back?

I have burning sensation in my upper left back -- sometimes there for no reason and sometimes after swallowing liquid and sometimes after eating any kind of food. I'm sitting here right now typing and it isn't extreme, but I do feel a burning sensation. I do get heartburn at night, have trouble sleeping and my mouth is extremely dry at night. I do drink a fair amount of water -- at least 8 glasses a day and I also drink a lot of soda.