Hi Natalie. I saw your post about the headaches and generally feeling awful. Please don't give up. Like Kat1e, I went through hell the first week. Muscle cramps, fatigue, headaches, the works. It helped that I took that week off work!
When I look back, it seems obvious to me that it's like withdrawing from a drug. The fact that I had it so bad probably means I was pretty badly "addicted" to and affected by carbs, and therefore REALLY needed to give them up. So in a way you could see it as a sign you're doing the right thing.
Pretty much everyone says that once you get through it, you feel much better and stop craving carbs. It really is a case of grin and bear it. If you cave in and eat some carbs, don't let it derail you, just start again! Best of luck.