That sounds horrible. I agree - if you're cleansing and you don't feel right...then DON'T. This cleanse is meant to rejuvinate us not hurt us. You should be very proud of your accomplishment and how far you went. Obviously your body needed more than the Master-Cleanse provided. Many say here "don't take this - don't take that" it's not part of the cleanse. I say hogwash - we owe it to our body to listen to it to avoid the dangers and pitfalls of fasting. Me - I take a potassium supplement every single day, along with my heart medication. Otherwise, I'd end up with an irregular heart beat and in the ER. If you do choose to cleanse again, you may want to consider taking a supplemental iron tablet if that's what your body needs. You're right - it's not in the book...but we all need to adapt to what works best for us (personally).
I hope you feel better after your rest, and are back to feeling 100% soon.