Chronic pain after craniotomy

I had a craniotomy for an optic nerve meningioma. The surgery was a success and I got a lot of my vision loss back. The issue is that I have had chronic scalp pain since the surgery. Apparently this is a rare occurrence and no one can tell me why it is occurring nor provide a good game plan for addressing the pain. I have tried accupuncture. I have been to an Integrative health center and a pain clinic. No one knows what to do. I am taking Lyrica twice a day which takes the edge off, but doesn't fully resolve the issue. I am wondering if anyone else has experienced scal pain after a craniotomy and if they have found a successful treatment.