Yes, the brain, prioception, vestibular systems and the eyes all move in concert. Brain injuries bring this relationship into sharp focus. I know 3 months seems like a long time, but I'm now almost 2 years, and I'm still in "recovery".

I think that you do need to rest, and the fact that you still have symptoms means that your brain is still not happy. Has your neurologist given you much of an indicator of what is going on? I.e. what was affected in your accident?

Have you seen a neuro-opthalmologist? This would help identify vision and nystagmus.

Was the inner ear affected? This would affect the rocky boat/dizziness sensation and nausea. A vestibular therapist can also help with balance and coordination issues.

Vision and vestibular systems are related but its a complex system and many doctors are not sure just how to coordinate care. I went to both ENTs and Neuro-opthalmologists as well as neurologists.

Daily, gentle walks at 5, 10 minutes do help (with sunglasses and hats to reduce visual clutter) as they force the brain to adjust. Icing the neck will reduce nausea.

But don't rush your healing as well. It does take time.