How is he doing now?
Honestly, I would try to get him to the ER as soon as he’ll go. They are set up to do a plethora of tests. Maybe it was just some odd, random seizure, but it could have been a heart attack, stroke, blood clot in the lungs, who knows? Have you recently traveled? They need to investigate.
At our age, you can’t screw around. The consequences of not following up are too serious. But I know how impossible it can be to force someone to do what they don’t want to, and how very frustrating it is!