Christina,
I also think the dizziness is related to your concussion. I would back off a bit from the exercise, rest and be optimistic that you will gradually feel better. I am wondering whether you may have pushed the exercise too hard and this set off your symptoms. I think that rest and staying calm will speed up recovery. If you start feeling better, then very sowly and gradually go back to exercise. I am convinced that this is not the end of the world, just a set back and in time and proper focus, you will be O.K. The dizziness, with no other explaination, following a head injury, is classic for PCS. Many health care professionals are clueless about this.
Nancy