Sorry about your Dad.
You didn't mention if you had checked the doctor's notes on the patient portal.
I know the issue of not getting the answers and information from a Doctor's visit. Usually there is someone who first interviews the patient to update the file and then the doctor comes in. And these visits are really not structured well to extract an update to patient status nor communicate information to the patient when there is a complex situation.
My current solution is to write a careful message asking the doctor the questions I want answered and sending it through the patient portal. Hopefully you are at an institution that has a decent portal. If your Dad is OK with this, I would try that.
In my past career we used to say it takes a long time to write a short memo - meaning one has to think things out carefully to be short. Be brief, professional and to the point in your message to get the best response. The doctor should answer difficult questions and not the support staff.