What Causes Recurring Headaches Along With Dizziness And Blurred Vision?

My daughter has been complaining of dizziness when she is sleeping, having headaches off and on for about 3 months. The past couple days she is having some blurry vision in one eye, she wears contacts. Last May , she got hit in the head with baseball, mild concussion, not sure if this is related at all. But seems the symptoms started after that. What do you think is the problem ? Should she get a head CT ? Pediatrician thought she might be dehydrated ... she raised her water intake , didn t seem to help .