I'm not qualified to answer your questions. Hopefully Chrisb1 will show up with an answer. I don't know where he has been lately. You may also try The Fasting Doctor over on http://www.fastingconnection.com/
You may need to have your fast supervised by a qualified doctor especially if it causes you to go into shock. I don't think you should fast if your in shock, but what do I know. Sorry I could not help you more.