Looks like your gallbladder has developed quite a muscle from your flushes. What kind of chanca piedra did you take? The liquid one? You might need a heavy duty quantity. Why don't you buy the powdered chanca piedra and make your own capsules? You could add boldo to it and have almost Pulverexx. You could also take that horrible Phosfood, the phosphoric acid that's used for the coke flush, for a few days. Go at it with the big guns before you give up on it. There is also the stone-breaker tea with gravel root, hydrangea, etc.
I read recently about the bear bile extract that's used in allopathic medicine to dissolve stones. It takes almost a year to get rid of stones on that protocol.