When patients turn to their physicians for diagnosis and treatment, they have every reason to expect that they will receive care of at least a competent standard. While medical professionals are, like all humans, imperfect and capable of mistakes, they are ethically and legally obligated to provide the best care that they possibly can. At minimum, they must provide diagnosis and treatment of a reasonable standard at all times.
When it comes to diagnosis, this reasonable standard is not difficult to meet. If a patient voices complaints and exhibits symptoms that would result in a competent medical professional arriving at a certain diagnosis, that diagnosis must at least be considered and pursued diligently by all medical professional