Hi, Post it - whatever you do, DON'T QUIT COLD TURKEY! The physical side effects are what Kittykat listed, but most importantly it can send you into a psychosis and mass depression.
Lamictal does not work from the first day. Therapeutic dose is recommended 200 mg, and it isn't an effective mood stabilizer by itself. It is to treat bipolar depression, it doesn't work on regular depression.
If you think it worked from the first day, it was a placebo effect, (you think it's working so it does), but that wears off.
Call your doctor immediately about this; if you are having these thougths, you need to check yourself in so you can stabilize under a doctor's care - quick!