What did the doctor think was wrong with Bob in "Needle"? Why didn't Clement say?

Question

In Hal Clement's novel Needle, after Hunter established communication with Bob, Bob and Hunter spend a lot of time trying to figure out how Bob can get back home from boarding school.

Meanwhile

He [the school doctor] learned nothing concrete this time, either, but he gained the impression that Bob had a problem on his mind which he did not want to share with anyone. Being a doctor, he formed a perfectly justified but quite erroneous theory on the nature of the problem, and recommended that the boy be returned to the care of his parents

Therefore

The headmaster wrote a letter to Mr. Kinnaird, explaining the situation as the doctor saw it, and stating that, if there were no objections, he planned to send the boy home until the opening of the fall term.

And

Bob’s father rather doubted the doctor’s theories, knowing his son remarkably well considering the time they had spent apart, but concurred with Mr. Raylance’s suggestion—after all, if Bob was not doing well, it was a waste of time to have him at the school no matter what the reason might be.

What did the doctor think was wrong with Bob, that his father didn't believe? There are a number of possibilities (homesickness, bullying at school, missing a girlfriend, having a crush on the school nurse (which would explain Bob's suspicious injury)), but Clement is awfully coy about what was suspected. Is there something I'm missing that would have been obvious to a 1950 reader? It can't be something discreditable since Bob's father is not outraged.

Answer 1

The doctor probably thinks he has what Freudians would refer to as 'Traumatic Neurosis'.

Following a substantial physical injury to his arm Robert has become sullen and withdrawn, as well as suffering a general weakening of his grip on reality.

...the headmaster and his staff were wondering about the cause of Robert Kinnaird’s suddenly developed chronic inattention, listlessness, and general failure to measure up to his former standards of performance—and it had occurred to more than one of them that it might be better for the boy to get away for a time.

...

He was doing the boy no physical damage, it is true, but preoccupation with the problem his guest presented and a number of too-public conversations with the concealed alien had produced an effect on Bob’s general behavior that was only too noticeable to those responsible for his wellbeing. _{^{~ Needle}}

There's also the possibility that he's mildly poisoned himself with glue(!)

She decided that the injury was not as fresh as Robert had claimed, that he had “treated” it himself with the first substance that he had found handy—possibly airplane dope or something of that order—and had not wanted the fact to come out.
...
...“In spite,” the doctor remarked, “of that silly trick of yours. What did you try to close it with, anyway?” _{^{~ Needle}}

---

Sigmund Freud described both the causes of this condition and the symptoms he seems to be encountering.

After severe shock of a mechanical nature, railway collision or other accident in which danger to life is involved, a condition may arise which has long been recognised and to which the name ‘traumatic neurosis’ is attached. The terrible war that is just over has been responsible for an immense number of such maladies and at least has put an end to the inclination to explain them on the basis of organic injury to the nervous system due to the operation of mechanical force.’ The clinical picture of traumatic neurosis approaches that of hysteria in its wealth of similar motor symptoms, but usually surpasses it in its strongly marked signs of subjective suffering—in this resembling rather hypochondria or melancholia—and in the evidences of a far more comprehensive general weakening and shattering of the mental functions.

_{^{Beyond the Pleasure Principle (1922)}}

Note that this ailment was extremely well recognised by the general public (more commonly referred to as 'shell-shock' in returning soldiers) at this point in history, hence why Clement hasn't felt the need to refer to it by name.