Suggest Treatment For Severe Migraine

Hi, My name is Christy and I am a migraine sufferer. I have been to two nuerologists in the past 5 years (new one because we relocated across country) and have been the guinea pig for quite a bit of different "preventative" measures. We have not had any luck and I still suffer from 3 - 10 migraines a month not to include the regular headaches I get frequently. I have changed my diet, kept a headache diary, and kept to routine when taking my meds. At what point do I look for another doctor and what type? Thank you