pain in upper left quadrant

I get a  pain sometimes in my upper left quadrant triggered by vomiting, coughing or sneezing, or maybe even twisting in an unusual position.  It started probably about 23 years ago when I got a sharp pain after I had vomited.  It doesn't happen that often, but it has been happening more frequently.  I do have a history of having very severe cough, and I did vomit a lot with all my pregnancies.  Now when it happens, I can even feel a hardness or knot in the area where the pain is. Once the pain subsides, all is well and the know goes away.  It is not too troublesome, but sometimes I wonder if it could be something serious.  Does anyone have any ideas?  Could it be a hernia caused by the stress of vomiting and coughing?