First of all, keep in mind that I am unable to diagnose you because I am unable to examine you, this forum is for educational purposes.
The symptoms that you describe are non-specific, and more information is need to tell the difference between basilar type migraines, multiple sclerosis or others. Basilar migraine headaches can cause vertigo, nausea and a sense of depletion. The treatment for these is usually a prophylactic agent such as elavil, topamax, nadolol, etc. Your MRI that indicates 'lesions in the [white]matter' of the brain is a start but you need a cervical spine MRI (both brain and C-spine with contrast) a lumbar puncture to look for inflammation (IgG index, oligoclonal bands) and visual evoked potentials. As far as the neurodengerative diseases that you mentioned (lewy body, picks) I would recommend neuro-psych testing for a baseline study and to detect any early signs of dementia.
I hope this has been helpful.
Good Luck!
JCmcc.
Yes,MS can cause lesions in the grey matter,usually they go undetected .Some technology has advanced to detect grey matter lesions with MS.They have limited resourses and studies are advancing in MS.Studies have shown at autopsy that 30-35 % of patients with MS had grey matter lesions.
If you google grey matter lesions+ms theres a wealth of info and studies.