Today I'm on my 31st day of a 40-day fast. Two years ago I did a 3-day fast and, like you, back then I drank nearly a gallon of water daily. That, I found, was a big mistake. Not only did it upset my stomach, drinking so much water, I believe, contributed to my dizzy spells and also heightened my smell. Smelling food everywhere drove me nuts, too.
This time, my 40-day fast, I'm barely drinking water and only drinking as my thirst dictates. When I do drink water, I only drink a few sips or one big drink. That usually satisfies my thirst. By drinking less water I'm not having any dizziness problems and I can barely smell any food around me; even though I'm cooking daily meals for my family.
Give it a try and see if that changes anything for you.