My daughter is on Lamictal and I was told that each time it is increased that some anxiety and agitation comes out for the first few days and usually levels off later in the week. I find this especially true with my daughter who was doing well and this week really noticed herself being more angry and mad than usual following an increase in titration. I think that this happens until you get to the therapeutic level. Is your wife already at the dosage they want her on???
Also with women....they will hormonally be worse during certain times during their cycle. Some doctors even work with them and have them increase the Lamictal during that time to help them through. It may be something your wife should bring up with her pdoc the next time she sees him.
Good Luck ~ Goody