Your right side pain could be some liver detox or gall bladder related. It's not likely anything to do with not eating.
Fasting is a tried and true practice which has been around for centuries and is rarely harmful if done correctly. It would probably be helpful for you to browse the forum and read some of the posts addressing the naysayers in our lives. We all deal with them, and unfortunately they usually are not interested in any kind of education to the truth of the benefits of fasting.
Stick with it (keep drinking, drinking, drinking), and keep reading everything you can which will encourage and help you along the way. God bless and fast ON!!