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.
5'0" female, 42 years old.
Started Primal October 31, 2011, at a skinny fat 111.5 lbs.
Current weight: 101.5. lbs and holding steady. Spring yardwork here we come!
Co-worker 1: Needs to lose ~50. Now he wants to start Mayo Clinic Diet. Yeesh. Give it up, man.
Co-worker 2: Needed to lose ~55. Lost 20 from stress. Started Primal in Sept, lost 20 more, but gained 10 back on a carb spree. We're working on it.