A question about water fasting please read and help how can I eat again?

I am trying a water fast and am just drinking water and no food. I read all this stuff on the Internet about it being good but I am on day 3 of not eating and just drinking water and I feel horrible my stomach hurts soooo bad, have a headache, chest pain , feel really weak, my legs feel like jello and all I want to do is sleep. The problem is that I have lost seven pounds in 3 days and now I'm terrified to eat because I'm afraid I'll gain it all back and more. I am starving but can't eat. How long have you gone with just water? How long can I survive? I'm 5ft6inches and am 114 pounds.