I had weaned down so I didn't get it, but I've seen a few exampled of delayed carb flu on the forums. Five days may not be long enough yet. You may have had a lot of glycogen and carbs stored up and you're body is still feeding off those. When it finally runs out and is forced to learn to use the fat, that's when it hits.
I'm on day 7 today and feel off. I woke with a really bad headache and generally just feel off colour. I'm guessing this is it. I felt a bit better after breakfast, so I'm hoping it wont last long.
Thanks all posters :-)