Elinora,
You've gotten a lot of great info here, as I often do. I hope you can stay proactive with your questions regarding all that was brought up here. Keep your symptom journal up to date with all of the test questions brought up here for your appointments.
I hope you find some answers. You're dealing with enough with the MG, let alone all these other strange sxs going on...
Hope and prayers for answers and quick treatment

PS I had low B12 levels too, which was thought to cause my cog fog. Took 1200 units of B12 and levels have been normal-though cog fog is worse