Your liver IS congested and this is reflex pain in the back from the liver that will last for a while until you get quite a bit of junk out of your liver. Keep faith and keep going. It's all worth it.
EDIT: That fist under your right ribcage is an indication you need a flush NOW, so start the Uphos drink and do one ASAP--that's 3 days after you start the prep drink. Do it every time this happens.
You'll learn soon that listening to you body isn't all that hard.