Hello and Welcome to ‘Ask A Doctor’ service.
I have reviewed your query and here is my advice.
First and foremost, clenching of fist is not a feature of Parkinsonism.
It is probably a voluntary act.
And he has denied that there is anything wrong with him.
Second, there seems to be nothing about slowing down.
That is one of the most important feature of Parkinsonism.
I would therefore doubt that he has Parkinsonism.
Having said that, since he has tremors, I think you should meet your
neurologist again for a complete examination.
Hope I have answered your query.
Let me know if I can assist you further.