For the past couple of days i have had a throbbing pain in my upper abdomen right below/around the left side of my ribcage. what could it be?

Abdomen/thorax pain: Most likely if this is a musculoskeletal injury it sounds like an abdominal muscle/rib cage muscle strain. This is usually caused from a twisting injury of the ribcage/upper torso. (commonly seemingly elliptical training with use of arms on the machine). If other abdominal complaints occur or begin to arise ( diarrhea, constipation etc) then a thorough exam of the abdomen is recommended.