Not sure I'm doing this correctly...

Hi. I am on day 5 of The Master Cleanse (strictly following the book) and drinking between 60-90 oz of water a day. I'm a woman who is 5'10 and 142 lbs. The only sign of "detox" I am experiencing is lower back pain for the past few days (started on day 3) which kind of concerns me that it's lasted this long, but it's not severe, probably moderate pain which lessens when I stand upright. I don't stink. I don't have bad breath. My tounge isn't really that fuzzy, just a little gray, but I can remove that with brushing. I do occasionally get a sinus headache b/c I have chronic sinusitis (sp?), but that's it really. By no means was I a healthy eater before this, so I'm certainly not "clean" already. What's going on?