My Father (92) is now impossible for me to take care of. No what?

He seems to be slipping into a mild form of dementia. I need help. He has not showered sense 2013, baby wipes is all he uses. I cannot get him to eat regular food an any schedule. He slips between calmness and agitation frequently. He has the opinion that he is of the utmost importance and if he does not receive attention when he feels it due him he goes off and a tirade. He pees in a can beside his bed instead of walking the length of the kitchen to the bathroom. His conversations are choppy and he forget, not what he wants to say, but how to say it. I have talked with his primary care doctor about a mental assessment and as dad knows when his appointment are, he prepares mentally of what he is going to talk about. Therefore the doctor sees no reason for such testing. Dr. Weisberger feels dad is going great for his age and believes dad just needs more exercise to ward off muscle atrophy. I have been caring for my dad full time as of 2012 and am beginning to realize he needs to have assisted living or someone who can take my place allowing me to return to my wife and children in New Hampshire.