The stones they are refering to are gall stones. When you flush your liver /gallbladeder you pass the stones built up in there (through your bowels). It is not painful to pass them during the flushes. Gall bladder pain is typically on the right side under your rib cage and can radiate up into your shoulder or around to the back. Along with a myriad of other symptoms. Could the pain you are feeling be a cyst getting reading to pop? I've heard people are able to rid themselves of cysts while doing the mc. Or it could be your bowels, who knows... Just keep doing the Master-Cleanse if you can you are probably clearing up some areas that need detoxing. However, I am not a professional, these are just my opinions. Good luck!