In dealing with tough problems like Autism, unknown autoimmune disorders, etc. Trusting a physician or even many physicians to make the right diagnosis is a gamble. It's even harder to find a physician who truly listens to the patient/family.

After much struggle with my sons rare condition, we found a physician who was able to help diagnose the problem. At one point he said "Your experiences in dealing the problem and the things your try that succeed and fail are far more important than my training... I'm here to help by listening and adding my experience"

In the case of a disease that I had, after seeing many many doctors and a year of tests, it was my dad on the periphery who figured it out exactly and then sent me to the right specialist.

Doctors are right some percentage of the time, but patients/families can have a great effect on coming to the right diagnosis.