Are you eating anything? One of the cleanse options is to eat just moderate amounts of vegetables. Try eating more veg or some organic eggs if you’re experiencing those sort of symptoms. I’m on day 4 as well and I had an omelette with salad for dinner because I was feeling quite weak today (omelette without milk/cream/Greek yogurt sucks by the way). Perhaps the stricter cleanse can be beneficial, but it may not be practical while working, so put your safety first and don’t take any risks. I think you cross a line when you go from hungry/craving sugar to actually feeling faint and shaking.