It is my understanding that the Epsom Salts dilate the bile ducts to allow the liver/ Gallstones to come out more easily.
You didn't mention if you are using something to breakup of soften the stones (like apple juice, or gold coin grass/bupleurum tincure)before your flush.
Milk Thistle helps to protect the liver by making the cell membranes less permeabli to toxins and it stimulates the growth of new liver cells, but it is not a liver cleanser live burdock, dandelion root or artichoke.
Perhaps you could look at a different Liver Flush method. Your body might need a different protocol.