Whatever your dad is suffering is because of stroke
and its complication.
Usually a patient with a stroke will have problem in swallowing. Some may have uncontrolled bladder and bowel also.
Because he suffered many strokes, the amount of brain tissue which is functioning will be too less.
Whenever he gets lot of oral secretions, make sure that suction is done, otherwise it will go into the lungs and can cause pneumonia
, infection of lung etc.