Fonty
Apparently the liver can excrete bile into the stomach during a fast, expelling toxins that way. They can go either way from the stomach and if there is a lot it can often try to force it's way out the closest exit. This is 'normal' and happens a lot during a fast, so hang on and you'll be much better off once all that crap is out!
Good luck getting through this crisis.
Take care,
Andrew.