With all my cleanses I have had an early period, and I know other women have experienced this as well. As to why it is dark and like the end of your period, I don't know why it's like that. I'd be weary of anyone who says they are SURE what is causing a symptom like that. But it's nothing I would be too concerned about unless further symptoms develop that complicated the picture. Feeling weak is a common effect of the MC. You may find rest, lemonade and molasses help you. During my first MC, working would have been difficult for me because I often felt weak and lightheaded. I've been working steadily through this MC, no prob. It all depends on you, how your body is reacting to the cleanse and of course what kind of work you do. Best of luck and enjoy!!