Wow, that's too bad! Soooo sorry it was so miserable. :(
I think perhaps you were dehydrated and the epson salts worked too fast. When you're dehydrated and then take the salts, it takes all of the fluids out of your tummy, and you still need SOME of them there - the stomach works best on a certain proportion of fluids to air to things to digest, about a third of each.
It also had already got to your gb and liver and the stones were probably moving, wanting to come out, but needing oil and juice to contract properly.
Did you keep sipping water all day after you stopped eating?