I also think it's important to realize to that experts, including doctors, can only work with the information they have available to them.
Of course it is horrible that Mr. Tweedy's wife was misdiagnosed, and yes, that particular doctor could also be inept (at best). I have certainly been to doctors, lawyers, and mechanics who are morons. I've also come to realize, however, that it is often the information *I* present that determines the outcome--not ineptness on the "expert's" part. This is true in science, as well. Just because something changes does not mean the scientist's initial conclusion was inept. As technology gets better, and the world becomes more accepting of science instead of burning practitioners at the stake as heretics, the "experts" simply have more information available to them, which may indicate that the theory/conclusion made with initial data needs to be revised. That doesn't make them inept or quacks, it makes them reasonable human beings. It's like growing up: you learn to see the world differently as you have different experiences. Your view will change on everything from how you feel about yourself and others to what kind of job you want. Most people would consider themselves "experts" about themselves, but their changing conclusions as they receive more data doesn't make them charlatans (which is a gross misuse of the word anyway, as pointed out earlier), or inept.
The (mis)diagnosis of Mr. Tweedy's wife was obviously a problem. However, it possible that her initial symptoms-- as presented--would be consistent with more than one thing. Doctors, like other experts, are not omniscient. Painful sex, for example, can be caused by MANY things, including vulvadynia, vagisimus, and endometriosis. And those are just the "medical" causes. Start adding in things like fatigue, lack of hydration, emotional stress/trauma, and there's a lot for a doctor to work through. So, for example, if painful sex was presented as the only symptom by a patient, it could lead to a variety of reasonable conclusions. Should a doctor test for all of those things? That's arguable, but generally it's accepted that you start with the simplest answer and work your way from there. Tests are often expensive and invasive, and unless we want to get into an argument about our nation's healthcare, let's just say that it's not always reasonable to test for everything that may or may not be wrong. Since vagisimus usually also has a large mental aspect to it, often being brought on by stress, trauma, or upbringing, it could be called "psychosematic." Endometriosis is also often severely exacerbated by (and in some cases caused by) stress--which would indeed make it possible to call it psychosematic (not necessarily politic, and not always accurate, but possible in some cases).
Just because someone is an expert doesn't mean they can read minds, or even always ask the "right" questions (in this case, for example, it's a pretty personal thing to talk about and could be embarrassing to some women). They have to go on what they are given, and what they can reasonably extract from the data. My point here is that an "expert's" diagnosis is often relevant to the information they are presented with. It is entirely possible that the above example is of a doctor who should be disbarred. They certainly exist. It is also possible that the doctor was simply not presented with enough information to make an accurate diagnosis. One makes him a moron, one makes him fallible. Neither makes the entire medical profession devoid of relevant knowledge greater than layman.