Jack,

Yep, sounds pretty normal to me. Most of us go through carbohydrate withdraw for the first several days. Some of the withdraws can be lack of energy, banging headaches. They will go away, trust us!

Have you been taking supplements? I've heard that some people get leg pains from a lack of potassium.

I've not had the back pain, except from my over doing it excercising. Possibly someone else will pop along with more information.