I've done the cleanse twice, the first was 28 days in May and I just finished a 14 day on Sunday. Both times I experienced dark vaginal discharge (looks like old blood). I am on continuous birth control and haven't had a period in over a year so at first it freaked me out, but I really think it was just another detox symptom (although kind of annoying) as it stoppped as soon as I stoppped the cleanse. I was tempted to go see my ob/gyn if it persisted but it didn't. I would say if you're concerned just see your doc to be sure or wait till you're done and see if it stops too.
As far as the weakness, I also had down days when I felt like not moving, but also have a job with 12 hour days and on my feet--what helped me immensely was blackstrap molasses (a tablespoon whenever I felt low), more lemonade, of course more water and soaks in Epsom Salt
baths. I couldn't have made the 28 days without those things.
You've made it 6 days, I would definitely try and make it to 10, your body will thank you.
Hope this helps!