[Buttons840]

There is always the possibility that we just won't know the cause of some medical symptoms no matter how much we test and investigate.

My question is, how often will we "just not know"?

So the doctors do some common tests and still don't know what's going on. From there, what are the odds that further tests will reach a helpful diagnosis, and what are the odds we will just never find anything helpful no matter how much we test and check?

[LorenPechtel]

While it wouldn't have directly lead to a diagnosis listening to her would have helped a lot. Note that they found the solution before they found the diagnosis.