Parkinsons or ET

Hi just wanted to see if anyone could please give me some advice. My dad had a check up for his hand tremor some years back. He was told it was then a ET, but now he is 75 years old and notice just recently he has a slight tremor in his lower chin. When he talks it is not there. He doesn’t feel or notice him. If anyone has any experience of this or advice would be grateful appreciated. Regards