Anxiety and sudden 'cold' feeling

I'm starting my next water fast, after a final cleansing meal of cucumbers, tomatoes, lettuce and parsley tonight.

I want this fast to go on for as long as possible. One thing that worried me on my last 3-day fast was a sudden feeling of anxiety that hit me on the morning of the 3rd day. My body suddenly felt chilled, for a split second, then I developed anxiety. It disappeared after a while, but still worries me nonetheless.

I really want to separate 'detox' symptoms from the signals my body gives me telling me to end my fast. Since I live in a country where fasting is not practiced, I have not been able to find a doctor to help me, and only have people like you on the internet to guide me. I realise this is a big responsibility on your part and won't hold you accountable for what might happen. Thanks for any advice.