Hello.
Your current symptoms suggest a neurological deficit more than your PTSD as a cause. The nightmares can, however, be part of the PTSD. You may need to get the tunnel vision, dizziness and fainting episodes evaluated from a Neurologist. It may even be something you can take care of immediately such as hypovolemia or hypoglycemia, but getting a Neurologist's opinion appears important here. As a side note, nausea with tunnel vision and fainting can be seen in Migraine.
As far as the nightmares are concerned, you may consider adding medication for reducing anxiety and for improving sleep quality.
Hope this helps.
Abhijeet Deshmukh, MD
(This post is for the purpose of providing medical information and is not a substitute for a face-to-face consultation with a doctor. This post is not intended to give or rule out a diagnosis, create a doctor-patient relationship or replace an existing one. I am not able to diagnose medical conditions online. Please consult with your doctor or a qualified healthcare provider for diagnosis and treatment options)