When fasting, always listen to your body. It talks to you every time you do something.
"Symptoms seem to increase when I drink the distilled water."
Ther's your answer. Your body is telling you that water you are drinking is not good for you.
If I were you, I would get a bottle of natural mineral water (no sparkling), and I would try to drink it for a day instead!
The greatest danger during the Water Fast for anyone fasting is in ignoring the messages they are getting from their body. Those messages do not come on your mobile phone!
Another greatest danger during the Water Fast is loss of macrominerals.
Macro minerals are Sodium Na, Potassium K, Magnesium Mg, Calcium Ca, etc.
You are drinking just water, and you are continuously washing out minerals from your body.
Every time you urinate, some minerals are washed out, but you do not consume any minerals while drinking distilled water only. Some minerals are washed out when you take a shower or a bath. Some are washed out if you sweat.
Some are washed out into your hair or your nails.
That may not be a problem for a short time fasts like 7 days, but any longer fast, and you should be getting concerned about the amount of water you consume, the quality, and the amount of minerals you may be losing every day ... etc.
Every person is different. There are people who can fast for 50 days on distilled water, because they have huge reserves of minerals, and/or they have kidneys and urinary bladder that are able to filter just water out, and keep the minerals back in the system, and there are people who can not do it.
If in doubt what group of people you belong to, listen to your own body!