Lamictal, in rare cases, can cause mania or agitation. My daughter is one of these cases. She and I are both on it and for me it has been a wonderful med. Certainly not the only thing I need, but it has helped with the cycling immensely. I still get breakthrough depressions and take Wellbutrin to help with that. I am on 300mg and have been on it for 9 years. My daughter has been on it for about a year, but reacts badly to higher dosages.
Do you chart your moods? Now would be a good time to start if you don't already. You can find some good mood charts online. How many hours a night are you sleeping? Are you coming out of a depression or have you been cycling for a while? If you feel like you're beginning to ramp up, let your doctor know. You could be one of those people who gets manic on Lamictal. I hope things even out for you soon.