Everybody's body reacts differently to the flush. Once you start flushing you start dislodging stones and blockages in the bile ducts. These movements can temporarily block ducts in new areas which will give you symptoms like the ones you describe. You will have to flush again after three weeks (two if the discomfort is acute) to push these blockages along the way. Drink apple juice a few days before the flush to soften the stones and make them exit easier.