My Dad Was Recently Put In The Hospital.He Has Never

My dad was recently put in the hospital.He has never had mental issues or a fam history of any.All a sudden hes seeing an talking to people who arent there.Hes in different years and places, anxious and noone can figure out why.Hes not a illegal drug user and is 50 years old.All they do know is he has a severe urinary tract infection.He is use to dealing with stress an has been for years.So though thats hasnt helped drs say that isnt the cause of this sudden an strange occurance.Any ideas i could pass on would be appreciated. Plz help