What were the three friends discussing? How jerome came to know that his liver was out of order

In a flashback, J. recollects how he once went to the British Museum to research a treatment for his hay fever, and after reading about diseases, convinced himself that he was suffering from every illness known to man except for housemaid’s knee. J.’s doctor, clearly recognizing the man's paranoia, prescribed him beefsteak, beer, walking, and good sleep habits, and urged him not to “stuff up your head with things you don’t understand” (10).

J. still believes that he suffers from every disease, but he is especially concerned about his ‘liver condition’ – the main symptom of which is “a general disinclination to work of any kind” (10).