Yes...or at least it was for me. By day 3 I thought I'd never make it.
More water helps, but once you get past day 3 or 4 it should go away. I gave up caffeine...did you?? The caffeine stop and sugar stop is what I feel my headaches were from. Stopping caffeine really helped me not cheat as caffeine made me hungry. I'm starting month 6 and loving the way I feel. It gets better. I'm here for you if you need help.
Explore this site if you haven't as there is loads of great info!