If he hasn't already your grandson should be properly evaluated by a doctor. I highly recommend reading this article regarding brain injuries. Recent discoveries are startling. http://www.1800nowhurt.com/?page_id=125
Additionally, you should find an experienced lawyer in the area of Traumatic Brain Injury and call for a free consultation.
It is difficult to evaluate your case based on the information provided. You should find an EXPERIENCED medical malpractice attorney and call for a free consultation right away.