About six hours ago, I sat down at the bus stop and felt an odd pulsing pain in my upper left abdomen, just under my bottom rib. Over these last few hours the pain has decreased but it feels...odd. Occasional twinges of pain are still present, especially if I take a deep breath, but it's mostly just a pressure that is now spanning from my left side almost over to the center of my stomach. I have GERD and currently take ranitidine, and though I missed my first dose this morning I did take my second shortly after I arrived home. I'm not sure if this could just be gas pain or something worse, and it has be a bit worried.