I don't know for sure if this is what you're going through -
During the first week of this fast I had a spinal detox, accompanied by the usual headache. It started on the very top of my spine where the skull and spine are connected and slowly worked it's way down my back. After the first week was over. It was somewhat painful, uncomfortable and even, at times, felt numb. It was very odd. I have never had a detox like this during any of my fasts, but the last three years have been torture for my body so it's easy to understand why I'm detoxing so much more. :)
I hope this is detox and that you'll be up bouncing around in no time. :)