My 17 year old son has been taking Lamictal for seizures for 2 1/...

My 17 year old son has been taking Lamictal for seizures for 2 1/2 years. He started out at 300 mg a day and was seizure free for a 1 1/2 years until November 2007. Since then his physician slowly increased his dosage to 500 mg a day. and he hasn't had another seizure . Unfortunately, Since the increase he has acne on his jawline and back. We are trying to find a way to get rid of the acne, but have been unsuccessful so far--decreasing his dosage is not an option as he has grand mal seizures. Also, he has these tiny red bumps all over his arms. His dermatologist say's they are a hair follicle problem, but I think it's quite a coincidence that they started when he began the Lamictal. If anyone has any suggestions, we would greatly appreciate them.