Then here's what you probably need to do. Keep doing flushes every couple of weeks until you get no stones a couple times. Even that, however, won't guarantee no stone finds in your gall bladder.
If you take some of the stones to an outside source for testing on your own, without going through your doctor, you will probably have better results than trying to convince your doctor to do the testing for you. It's gonna cost you some cash to do it, but that's really the only effective scientific way to do it. You need to get outside the bias of modern medicine to get this analysis performed.