I was in a car crash where my car went airborn and landed on it's side.

The first thing Dr. prescribed was vestibular therapy and the eye exercises made me feel horrible. The problem may not be your vestibular function but your visual system. It took me a year of doing therapy to realize I was barking up the wrong tree.

Google the symptoms of convergent insufficiency. This is what I had and has to do with your eye's ability to track objects. The result is headaches, fogginess, difficulty concentrating.

I suggest seeing a qualifed neuro-opthamologist that can evaluate for this condition and prescribe tinted/prism glasses(I wouldn't recommend vision therapy as it's more expensive and glasses can provide immediate relief for some). Hope you find relief.