Paleo Headache and Fatigue

I'm not sure if my current gluten-free, dairy-free, sugar-free, alcohol-free, caffeine-free approach to eating is considered a true paleo diet, but it seems like it would fit the mold. After a day, I can tell you I noticed a change. And that change came with a dull headache during most of the evening. Was it caffeine-withdrawal or a serious need of a sugar-fix? Who knows. It turned out to be a pretty exhausting day at work, as the days of registration and check in at a large high school can be ... quite a bit of work. So, on top of a long exhausting day during which I consumed far fewer "quick-energy"-producing calories, I was just tired. Slept well though. That said, I am interested in how I will feel when I start working out. The hope is - eventually - that I see some noticeable change in my energy, strength, weight, fitness, and clarity. I'm expecting that there will be at least a few days of feeling different in a lethargic, detoxing, sort of way. That said, my goal is to re-charge, so that maybe someday, I would be motivated enough to do something like this: