itchy skin is directly liver-related. And since the liver and the kidneys do a lot of work on a water fast, what can't go 'down and out', (because food is not 'pushing out' eliminations, or supressing 'symptoms', the way, say, eating certain things will distract and busy the immune system), and what doesn't get burned up through autolysis
fast enough, then tends to go out the skin.
Everyone is different, in the way their bodies deal with toxins, and how the system determines what is important when it comes to the housecleaning order-of-operations in a Water Fast . . .
When you are not water fasting, back on food, try doing some liver-rebuilding things. And maybe some liver flushing, also. Eat an apple a day (or more) for awhile. They really are healing! You might also want to try supplementing with diatomaceous earth in a g;ass of water daily,(food grade only!), which both provides silica and trace minerals, and absorbs any number of toxins, pathogens, heavy metals, ets. and removes them. This helps the kidneys and liver, and cleans the whole GI tract, top to bottom, over time. Bottom line- When you do eat/drink, let your food be your medicine--and think of what's good for the liver. And the kidneys.
The D.E. helps. And cannot hurt you. You can take it as nourishment, every day. (not Water Fasting though)