It's a good idea to prepare several days in advance for liver flushes. Drink lots of water, Eat lots of magnesium and potassium rich foods; Make sure all your minerals, and electrolytes are in check. I find that if I do this, I tend to have very good flushes: No nausea, or vomiting.
The rule is no water after 2:00pm. Dr. Clark states that if you eat, or drink after 2pm it could make you feel sick. I am sure there are exceptions however.
It takes practice to learn what is right for your body, I am sorry to hear you were so ill..