The left side where the colon bends and corners down from the transverse colon to the decending colon is a notorious place for parasites to hang out.. That's where my big ones tend to be also. Its also a place where constipation can occur.. just underneath your left rib cage.
Lots of ways to flush the liver but the Liver Flush I was referring to is detailed here //www.curezone.org/cleanse/liver/huldas_recipe.asp
It is not for the faint hearted as it is quite a procedure. Liver pain is on your right side, so it sounds your problem isn't in the liver but in your colon but you might want to keep a Liver Flush in mind sometime down the track after you've cleansed your colon. Its a really good cleansing protocol after you've done a bowel cleanse.