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, 44 years old. Started Primal October 31, 2011, at a skinny fat 111.5 lbs. Low weight: 99.5 lb on a fast. Gained back to 115(!) on SAD chocolate, potato chips, and stress. Currently keeping food tracker.
I (try to) follow by-the-book primal as advocated by Mark Sisson, except for whey powder and a bit of cream. I advocate a two-month strict adjustment for newbies. But everybody is different and should tweak Primal to their own needs.