If the pain changes due to drinking water or when eating or going hungry, then it's not totally liver, altho the liver is involved of course. But drinking water would affect the stomach acids more than liver. Chances are good that your entire digestive system is weak and having to work too hard, so you need to follow the guidelines for increasing digestive power on page 13, lower your stress (try not to react to situations outside your control), and start liver flushing.
If the pain is localized to your abdomen area, it's usually stomach and small intestine that is impaired the most, liver second. If it shoots up to your shoulders and/or arms, then the gallbladder is involved and the problem is more liver/gb than stomach/small intestine.
As much as I admire Dr. Cabot for her liverdoctor.com site and knowledge and hope that everyone reads it, I'm not a big fan of Livatone. It's a good one to start out with for general detoxing of chemicals, but for long-term tonifying, increasing bile and cleansing of fats and such, Planetary Formula's is better.
Hope that helps! :)