V.W.
Any chance you have missed out on normal caffeine intake today or yesterday? I have only had a caffeine withdrawal once... and it was because I wasn't a regular coffee drinker EVER.. until after my kids were born I started having a cup in the morning since my husband drinks it. Well... little did I realize that I had gotten used to that little bit of caffeine every day.. one day I was busy and forgot... next day... I was SO sick. Not just a headache, but nausea too... it was awful. You can get addicted to caffeine in sodas just as easily... you don't have to be a coffee drinker.
Just a thought...