Your liver is dumping all of the toxins into your intestines, ending up feeding the bad microbiom in your large intestine.
You most likely got auto intoxicated by the content of your small and large intestine.
Any time you have any problem during the water fast, you take an enema. And, if it does not help, you take one more, and one more until you feel better .
To prevent similar problems, you should have done a serii of Liver Flushes before you started your water fast.
Also, water enema the first few days of the fast can help a lot.