Dan a 16 year old got hit in the head during a lacrosse game. He also has night terrors (which initially interests House) and then House sees his leg twitch.
How House gets involved
Cameron had been answering his mail and she wrote back to the boy's parents and gave them an appointment.
Sexual abuse is House's first guess. Then later the team decides it is multiple sclerosis.
The privacy invasion / major ethical breach
House does DNA tests on the parents
The final diagnosis
Because his biological mother had not been vaccinated, the kid was not sufficiently protected measles and "once every million or so times, the virus mutates.... of Dan having a fever and a rash the virus travels to his brain and hides like a time bomb. In this case for 16 years."
The clinic patient(s)
Guy with a really nasty pussy abscess on his knee who has sued other doctors. House treats the knee and when patient serves him with papers, House tells him he has diagnosed gonorrhea.
The music playing during the closing scenes of this episode was "On Saturday Afternoons in 1963" by Rickie Lee Jones. This is available on the CD titled "Rickie Lee Jones". You can listen to a sample of this song at Amazon's pages on these albums (click on the album title here and again at Amazon then go to the bottom of the next page to get a choice of which song to listen to). Identification of this song provided by Sanlin. This album also available from Amazon UK in Briatin.