if the water and salt don't help, it's also possible that you picked up a bug somewhere, i've had a few friends coming down with summer colds/flu's. salty broth should help that too.

usually you wouldn't get induction flu if your carbs are too high. maybe if you had some higher carb days and then went back to vlc you could trigger an induction flu.

also magnesium can help. there are a few threads on here about the magnesium