Hang tight. Fasting/cleansing can also be an emotional rollercoaster. As long as you understand this and not go along with the emotional upheaval unchecked fasting can be quite "enlightening". As I sugested before to "self observe" there is much to be learned about with what you identify as "I". For me this inner journey part was the coolest part of fasting besides the obvious health benefits and to this day is one of the most powerful things that keep me coming back to the long fasts.
When we fast we are literally changing our body chemistry. Everything and I do mean "Everything" including every thought we have involves some kinda chemical reaction. When you change your chemistry you literarlly change who you are and this is where the really cool part comes in when you "self observe" in that you are afforded an inner view from an "I' that you've never experienced before. Most people waste this very unique opportunity because they get all wrapped up in every single physical nuance or obcese over weight or some other emotinal issues and all their energy is wastedby whining their way through the fast.