First, no supplements during a water fast. You deplete your nutritional reserves when you eat partially. Just drink warm water, rest and stay warm. All symptoms you describe are part of fasting and detoxing. When you break your fast, you may break it with freshly prepared tomato juice and lime or lemon. Build your appetite slowly with plant based juices and then salads. Then going forward stay away from fruits, all forms of Sugar that includes grains, meats, fish, milk products, chicken etc. you may have eggs. Every meal should include either, Kimchi, Kefir, Kombucha, Sauerkraut and Yogurt. This will build your gut microbiome. No alcohol at all, so limit the Kombucha.
Veggies are a good source of feeding the right bacteria in your gut. After a month of such diet, take good probiotic pills.
This will be a lifestyle change for you and good for other conditions you may have.