My Father Has A Severe TBI As A Result Of

My father has a severe TBI as a result of an industrial accident in 2010. He does not communicate, and requires total assistance for everything involving his day to day care. For the last 3 weeks, he has been moaning, and sometimes even yelling, moving his head continuously left to right, and rolling his eyes back. It looks like he is in pain, but I cannot find a source. He has a VP shunt, which has been checked out, and is properly functioning, has had an EEG, with results showing more "background" than before (I am told he is more awake), and all sorts of blood work, which have come out to be normal. I have taken him to several doctors, and no one has been able to find what this is. In your professional opinion, what could this be, and is there treatment?