Could you be in major caffeine withdrawal? Or could it be allergies or sinus irritation (maybe due to low humidity/changing weather systems)? Don't give up, you'll figure it out! Rather than giving up entirely, consider raising your carbs slightly with good vegetables and fruits and see if that helps. But first, as Natrushka said, definitely check your vitamins, you may not be getting enough potassium and magnesium. Feel better!