A first step is to try to identify the organ system involved:
That area of your body contains stomach (should have some ties to eating or change with antacids or Pepto), spleen (tends to be a dull pain, associated with nausea, and lasts longer), the corner of the colon as it turns south (could be, might change with simethicone, Gas-X and others), ribs and muscles (often positional as well as breathing related, responds at least somewhat to regular pain medicine like acetaminophen or ibuprofen). You might weigh more than you want but certainly not enough for that to be a factor. Some medicines can cause muscle pain (cholesterol medicine comes to mind). With your doctor's knowledge and blessing, you might stop or hold each of your medicines for a few days or long enough to be comfortable that they are not a factor.