If they do an MRI, they can tell lesions from Migraine from other types of lesions like those seen with MS.
I was watching Dr Oz a week or so ago and he was talking about the supplement Butterburr as a great preventative for Migraine. Its 75mg 2x daily. May want to give it a try. He said it was very safe.....do a little online research.
So sorry you have such terrible headaches. Hopefully you will get some answers soon as to whats going on.