Re: Heartburn during water fast
I think the advice you received to include salt in your water is incorrect. There are many different minerals that your body uses as electrolytes, the main two are sodium and potassium but there are others as well. Taking just more of just one of these (like drinking water with salt) will actually cause much more of an imbalance in the electrolytes than taking nothing at all. That being said, it seems unlikely that your electrolytes would go out of balance that quickly (only two days, and 1/4 teaspoon of salt shouldn't have much of an impact). Maybe your body is really just cleansing itself like crazy, in which case this is really good, especially if you have a terminal illness that could explain the terrible symptoms you experienced.
As you said, I would take a little break from fasting and then try again in a bit, this time only drink plain water. If you have the same type of problems, then it is probably your body expelling tons of toxins. Generally, I would say if you get sick while fasting it is good to keep fasting, but vomiting during fasting could be dangerous as your body is losing electrolytes and other nutrients without being able to replenish them.
Any reason why you are not posting this on the Fasting: Water Only forum?