As you may have experienced yourself, sometimes, when people are chronically ill and go to lots of doctors, the doctors conclude that there is nothing medically wrong. I think it's important in these cases not to jump to a conclusion too quickly about why it has remained undiagnosed and to take seriously *all three* of these possibilities: 1) Diagnosis Error: It's a non-standard presentation of a known disease or a rare (or frequently missed or misunderstood) disease, making it hard to g...