ditto what nicki said about the switching from carbs to protein causing tiredness.
as for calcium, i eat greek yogurt on a regular basis and it doesnt effect my diet at all. actually sometimes it makes me feel better

however its true that you can get plenty of calcium without having dairy in your diet. some of us bend the rules a little, if you keep things flexible then you end up being able to stick to it longer. Grains are my worst enemy, I have maybe 3 servings of grains a week at most. but this is due to having a hard time finding palatable alternatives to some recipes that require grains. the way i see it so long as grain is considerably reduced in your diet you should be just fine.