What Causes Tenderness Under The Left Rib Cage In A Diabetic Person?

I have noticed tenderness on my left side just under my rib cage; now that has become increasingly more painful throughout last night and today, painful to the touch, to twist my waist, or bend and it is painful to sit upright or stand as I feel pressure in the side where it is tender. My adult daughter looked at the area, there is no discoloration, although she seems to think there may be some swelling based on the look and feel of the right side. I am a type 1 Diabetic, if that is helpful. On an anatomy diagram I would guess that my spleen is the organ most closely would be the organ that may be being affected?? Although, I have not been in any accident or sustained any injury. Should I be concerned?