For a couple of months now, I have experienced pain behind the lowest part of my right rib cage; I also feel it in my back at the same area, and occasionally on my side. Sometimes all three areas at the same time. It is most prominent when I take a deep breath, or have been sitting in a stationary position for more than an hour. I thought at first I might have pulled something; but it just won't go away. The level of pain lightens up and worsens for no good reason.