There are some people who will never, ever complain about anything. When they complain of severe abdominal pain, for example, you pull out all the stops immediately to figure out what's wrong, because it's probably really bad.
On the other hand, there are hypochondriacs and people will low pain tolerance. While they can certainly also become seriously ill -- and one must never forget this -- the tempo and pace of workup and order of intervention is markedly different, absent other information that shifts the pretest probabilities.