Men who won't go to the doctor are a real pain. My sister experienced this with her husband (different problem) and decided to just tell him she was worrying, and would he do it as a favour to her. She doesn't ask him for much normally, and he agreed.
With my son, I just made the appointment.
Like you say, you can't force him, only ask him and reassure him that whatever the problem is, it's better caught early.