Hi guys, I too am on day 4, but no back pain for me (don't mean to rub it in) But my thoughts are that it may be (from the position you are describing) cramping of the intestinal walls. Lots of times when you have cramping/inflamation in the lower regions of the bowels it may show up as low back pain. My guess would be that maybe you are drinking too much of the lax tea and maybe not emough water? are you doing any of the PB shakes? If so you are probably only in need of more water. Are you doing the SWF (Salt-Water-Flush) in the AM or just the tea?