Apparantly it's normal to feel like garbage when starting a gluten-free diet.  I remember a few days after I stopped eating Wheat (and most Gluten) for my diet requirements, I had three days of headaches, hot flashes and some nausea.  I guess you end up having Flu-like symptoms on such a diet.  My Homeopath told me it was normal and that in my case, my body was flushing out the toxins (or rather what it thinks are toxins) due to food sensitivities.