blown it - what now?

Hi - I was on day three of my first master cleanse until about 10 minutes ago, when I ate a plum and some tofu. I gave up because I have such a headache and after three days of it I can't concentrate on work and am wondering whether this is my body telling me that I'm damaging myself.
My question is - having eaten, would I be better off to just go back to normal, or should I try again tomorrow, assuming that the headache is gone?
Thanks in advance.
Cathy