I tend to agree with his Doctor. He is clearly selusional, and also a bit paranoid, from what you have said.
It is quite usual for people in his position to think thatb they are fine, when in fact they are not.
He would benefit from a full psychiatric evaluation, so that he can get whatever treatment he might require, but of course, as things stand, he has to agree to that himself.
Until someone with a problem accepts that there is a problem, they won’t do anything about solving it. That’s the first hurdle. The second is convincing them that help is available, and that the should accept it.
Sustained gentle persuasion is at least part of the answer. Just being there to listen, and letting the person know that you are there for them may let them build up enough trust inside themselves to begin to deal with it.
You may not to be able to solve their problem, or for that matter understand how they feel, but just listening and letting them talk can be really helpful.
Getting people to open up can be difficult. It has to be done sensitively so that the person does not feel put down or alienated. A gentle approach like ‘It must be difficult feeling as you do. Perhaps we could talk about it? is often the best start.
Choose your time and place carefully if possible so that the person feels as safe and as comfortable as possible.
Try to make sure that the person feels that you are on their side, and try to use ‘open questions’ – ones that don’t allow a simple “Yes” or “No” answer.
Don’t try to give them solutions, because as they open up and talk, the person begins to find their own solutions.
Good beginnings are:
Where – 'Where did that happen?'
When – 'When did you find out……?'
What – 'What else was happening?'
How – 'How did you feel?'
Can you tell me…….
How are you feeling? This helps to get past the bare facts of a situation, and lets people begin to look at their inner turmoil.
Don’t push hard or try to tell them what they MUST do – give them space and time to talk.
For now though gentle persuasion is about all you can do, and of course, observe his behavior in case there is a sudden worsening of his symptoms.