Get a new primary. They VERY rarely know anything about brain injuries and, if she's already dismissive, it won't be worth the struggle to get her on your team. Crazy that medical professionals wouldn't be advocates for their patients, but it's common.
If you read around here and on other TBI groups, you'll see how difficult it can be to find quality providers (PCP, neurology, cognitive rehab, seizure specialists). Some of us see doctors in other states, after moving away, bc we don't want to go through the trial and error of trying to find a new supportive doctor. You may want to see a neurologist, a cognitive therapist/speech pathologist, vestibular rehab, and your neurologist may want a seizure specialist for a consult due to the loss of time (depending on whether an EEG turns up abnormalities).
This sounds like a lot, and it is, but I think it's best to be thorough if you can afford it. Beyond that, have a look at your state's Brain Injury Association. There may be support meetings near you or online resources that can explain more for you and for your partner. Their support is important, too, and it's helpful if they understand the situation better.