What Causes Recurring Episodes Of Migraine Along With Double Vision And Fatigue?

I ve had migraines for 9 years however in the last year they have increased and I ve also started to experience horizontal binocular double vision which can be corrected by prisms since last May. However midway through a bout of headaches, pain scale 6-8 with severe fatigue, that last around 4-6 days depending i get additional double vision that is Not corrected by the prisms. This resolves itself a few days after the headaches/migraines cease. I m on topomax for the migraines and frovex. I ve had mri s which were reported as clear. Is it possible that the migraines could have affected the sixth nerve and are causing a temporary issue/impact/damage resulting in this transient issue that presents similar to a sixth nerve palsy?? Many thanks.