As IC said, listen to your body, you will know if something is not right.
You may be Magnesium deficient. Try Epsom Salts in your bath water. If you have Boots store near you they should have ES.
Is orange juice from supermarket? If so, done is done, but try not to drink that again. Freshly squeezed is the way to go. Also no toothpaste, brush your teeth with water and scrape your tongue.
Stay warm , rest and drink warm filtered water as per thirst. Sleep does get erratic during a water fast.