Difficult to start something 'new' on the last three days of the old moon; you don't tend to feel a lot of 'support'. But the short answer is- yes. very normal. Much depends on how you are, going into the wfast. Your toxic load, etc. Here is the good news: it's a new moon this evening; day 3 is often the hardest--and then, you turn a corner. Please do a search on EFT, on this forum; it has helped countless people deal with the ups and downs of a water fast. It is a form of no-needle acupuncture, that simply resets the energy pathways in the body, so the blockages are cleared.
We hold emotions in the stuck places, hence :Emotional Freedom Technique. You start with giving your feelings/thoughts a number from one to ten of intensity, and then after a few rounds of "tapping" (very simple to learn), you are often at 0, or at least much less (upset). Sometimes the discomfort is still there, but the feeling of being bothered by it is what's relieved. Don't underestimate the power of such a tool.
(Some people might try an enema - there are two distinct camps on this subject. This has no relation to EFT, btw! I just thought to put it in brackets. I've never done an enema myself, buu to each her/his own.)
Hang in there! Make sure you are not dehydrated, and that you are not holding your breath--as people tend to do, when uncomfortable. Sometimes, for the nausea, boiled water, sipped can help a lot. Or, a bath. For the headache, as Chris sometimes says, you might have to 'grin and bear it' -or a cool or warm cloth, as sounds appealing, on the neck...
try not to fixate. and make your self-talk something positive, like "you're doing so well. Good for you. :-)
When you feel like it- the recommended messages
here can be inspiring to read. Otherwise, sleep often is the balm.