I too have Migraines and MS, although I've had migraines for a lot longer. I take 400 mg a day for migraines as 75 didn't even touch them. When I tried to titrate down to 375, I got a headache, so 400 is my dose.

If you are getting break through headaches, you might want to talk to your doc about titrating up your dose...

It might not hurt to see an ophthalmologist. I hope your headache is gone and stays away!