What is the reason for blabbering irrelevant things?

Hi doctor,

My father had a long two months of hospitalization after a bypass surgery, where he developed sternal infection and later developed hyponatremia (low sodium). Since he was not in his senses for quite some time, a neurologist diagnosed him as a probable case of extrapontine demyelination. Although after some time, he showed better signs of consciousness and within next 15 days he was back home and went from being bedridden to doing everything by himself after some help from physiotherapy. Although after he realized he spent almost three months in hospital, he started getting depressed. Nowadays, he stays in a kind of crying mode (no tears), does not talk properly (talks in a weepy tone), has no confidence in himself and says he cannot even move by himself (although he can). He even does not want to go out anywhere. At times he blabbers weird things. Also, at times he does not realize about the nature calls and poops in his pants. I am not really sure whether to take him to a psychiatrist or a neurologist. Who should I consult and what should be my next step? How do we take care of him now? Any advice related to neurologist or psychiatrist. What kind of treatments should we go for now that would be helpful? Please guide.