I do not see any reason for you not to wait two weeks. I do not think that you are having pain in your gall bladder since you say it is in your lower back. I have had this slight pain before after a liver flush. I have done 23 of them. The pain has left the next day.
If you really think you need to do another one right away there probably is no harm in it. I doubt that you will get stones out. It is recommended to wait a couple of weeks so more stones can move forward toward the gall bladder from the liver so they can be flushed out.
I think you need to drink a whole lot more water. We need to drink half our body weight in ounces of water daily. Other fluids do not count toward this goal. A 150# person needs to drink 75 ounces of water every day.