Simple reply, Hayley, is that your head hurting is your body's response to your fast. If you're fasting to de-tox, you were detoxing big time. Stopping your fast meant stopping the de-tox. I'm typing this as I endure a MASSIVE headache (I never get headaches otherwise), but I know my body's working its hardest to do what I've enabled it to do by stopping caloric intake. I understand you may have had to stop for work or other reasons, but, keep in mind, your body (like mine) must have a ton of stuff to get rid of. I've had 3 operations in the last 18 months, so all of the anesthesia and pain meds are likely the cause of my headaches (and now leg aches). But that's what I signed up for, so I'm going to try to gut it out. The other responders are correct, though, in suggesting you clean up your intake and ease into a longer fast with a series of shorter ones. You'll get it: not everyone would be adventurous enough to even try it, let alone stick with the headache you endured for the couple of days you did. Keep at it. Listen to your body. You'll get there, and you'll be rewarded when you do!