Statistically speaking, you were making that all up. Of course in your case it turned out to be serious, but think about how negligible the odds of that are when you're seeing dozens of patients a day during your career.
Also, when a patient succeeds in getting a correct diagnosis after trying multiple doctors, the previous doctors generally will not find out about their mistake, so there's a bias against them actually learning the right probabilities: you can expect them to be overconfident on this score.
Using "chance of occurrence" is a major logical fallacy for diagnosis identification and can ruin the whole practice.
https://my.clevelandclinic.org/health/diseases/9833-munchaus...