Oh, carb withdrawal, how I loathe thee.... =) My symptoms are hunger/cravings, headaches, and being a major crab, but some of that may be more psychological than physical. =) It will pass! You'll feel so much better once you're eating healthfully.
I'm vegetarian as well (not vegan), so I have a hard time cutting carbs and getting enough protein. I focus on getting my carbs from fruits, vegetables, and whole grains. I cut out simple carbs and keep the rest. I also try to get more protein from dairy sources, soy sources, and protein powder when needed.
Best of luck! You'll do great. =)