Cluster Migraines

I am a 52 year old female who has had migraines my whole life, even as a child. As I have gotten older they appear in batches. During this episode, I have had about 8 or 9 migraines in the last couple of weeks. My doctor tells me that they have become "cluster migraines", but she doesn't say why the change. The last time it lasted for two months. She has prescribed Frova and tramadol which help, but don't totally prevent them. I was on immitrex for years, but little by little that became less and less effective. During these episodes I accomplish very little because all I can do is nurse the headaches. PLEASE HELP!