The doctor rings true. I had 3 separate doctors on 3 separate occasions diagnose my 21 month old son with an ear infection, instead of the plum-sized malignant brain tumour that it was. From their point of view, pediatric brain tumours are very rare and ear infections are common. Their 99% heuristic almost killed him. That was 2010. He survived and is now a vibrant 13 year old, but only because of one curious intern/…
This one is difficult. The first doctor with the first diagnosis was likely doing the right thing. Although tragic, it's exceedingly rare for someone that young to present with a brain tumour.
If a doctor was ordering CT scans every time someone arrived with ear infection symptoms, they statistically be causing more harm than good. CT scans raise an individuals risk of cancer ever so slightly. Not a big deal for individuals, but scaled up to an entire population it's actually a real creator of cancer risk.
Now obviously if you have some serious symptoms then the incremental risk of a CT scan is less than the risk of missing a serious diagnosis. However, jumping straight to the CT scan without good reason would be a mistake. So now doctors are in a position where they must integrate diagnostic history into the equation. Showing up to multiple doctors with an "ear infection" that isn't responding to any treatments warrants deeper investigation. If the issue isn't resolved, proceeding to imaging makes sense.
This is why it's important to begin return visits with a summary of what's been done so far. If you get a doctor who wants to re-start the diagnostic process without accounting for previous work done so far, unfortunately the only real solution is to move on to someone else.