My Father In Law (79yrs) Has Had A Stent Placed

My father in law (79yrs) has had a stent placed into one blockage of his heart but there were two other older blockages that would need open heart surgery to fix. He is not willing to have this done as he has had a triple bypass years earlier.
He had the stent done about 3 weeks ago and this past week he has been sleeping alot more than usual, unable to dress himself, confused, disorientated. I saw him Saturday and he could not undo his zip on pants to urinate then he wet himself. He is a cattle farmer and was letting cattle out of yards where he would never have done. He was obsessed with a gate latch for 15 minutes stating it was broken...but it has been broken for years. We took him to hospital that afternoon and he was admitted after not being able to do some particular tests the triage nurse was asking him to do. On Sunday he was discharged all ok with no treatment. He seems absolutely back to normal and is fine again. My question is what could have happened to him? Heart attack? STroke? Concerned hospital discharged him too soon.