YellowBird,
Yes, he started to rest on day 4. Because he told us only on day 3 in the evening.
You mentioned that you had headaches before the concussion. He did too. Sometimes stress related, sometimes wheather related headaches. But advil worked before. And after concussion - nothing works. And all the doctors ( we saw 3 different doctors) told us that because he had migraines before it will take longer to be headache free for him now.
I am not sure what brand you can get from US, but we are in Canada and I bought Jamieson brand. B2 100 mg. i am sure you can do your research. Good luck!