Did you avoid caffine before starting your fast? Caffine withdrawl headaches are very common. You will feel tons better once you get all the food out of your digestive system. That is way many people have more difficult days two to three. You could also be having detox symptoms. No time is too early for your body to start cleaning itself.
I suggest you drink the required amount of water (1/2 your body weight in ounces) and continue to use your lax teas and/or SWFs to flush out old food and toxins. Hang in there; the Master-Cleanse is full of highs and lows.