I agree he needs a serum metabolic panel performed with BUN and Creatnine performed. Also for the record, WHAT ARE HIS BLOOD counts. A Oxygen saturation is meaningless if his Hemolobin/Hct are much below 10 and 30 respectively. Even with good oxygenation this can lead to hypoxia in the the brain and confusion. Is he still on ADT?
I would give chemo a try as its toxicity is not THAT bad and if he responds well then it is worth doing.