Ok, there's a lot to unpack here and you really had the deck stacked against you. First, lets go from the top, once a test says X, disproving that X is really hard. And that's not unique to the medical profession, it's inherent to all humans and we suck at revisiting or revising our decisions, much less at looking at the possibility to even reverse it.

Which moves us to the next two issues: liability and time. Any moment that you ask someone to revise a decision and specially with the stakes that the medical profession has that nobody has the time nor the inclination to open themselves for a mess.

Now, if you really want to be successful, you have to, before they even have a case with you, and specially before the diagnostic loop closes, to suggest the tests that the study has, since that has the biggest chances of looking at the right thing to look. Just be straight that you walked in with a theory. Doctors notice when they're being steered way faster than they notice when you're actually right. That's how you work with the systems that have a overworked mass trying their best.