There are of course many diverse opinions pros and cons on the use of drinking distilled water while fasting or not.
The symptoms you have described nomoreMS when switching to distilled water on your fast really means that you were only postponing the inevitable elimination of toxins from your body, and where the use of mineral water (or any other water) was just masking/preventing elimination via "stimulation" from this type of water, and giving you the illusion of more strength.
Switching to distilled revealed the real underlying symptoms that you should have been experiencing if just drinking pure H2O.
I would like to remind those of you who are against its use to consider this...............
The argument against the use of distilled means that viewpoint is against the natural cycle of precipitation, which provides distilled water within nature via evaporation/condensation/precipitation/rainfall.
This is the water in its natural element that we are all designed to drink, just as the water contained within the fruit and vegetables that you eat also contains distilled water via nature.
Paul Bragg and Jack LaLanne are protagonists of drinking distilled water, and where I suggest that anyone interested in this topic should read Paul Braggs book: "Water--The Shocking Truth".
There is no doubt in my own mind that distilled water is the preferred choice in cleansing and healing the body.