Suggest Treatment For Symptoms Of Splenic Flexure Syndrome

I believe I may have splenic flexure syndrome. I am a 54 yr old woman in good health. I get a severe pain like a side stitch, just under my lower left ribs. It usually happens only when I sit for long periods (like a long ride in the car), and is generally relieved once I stand or lie down for awhile (but sometimes I can't do this if I need to get somewhere). I have tried simethicone, antacids, tylenol, ibuprofen, even vicodin with no relief.