Merry Little Christmas - S3-E10
Other mistake: Just by looking at Abigail's mother, it is obvious that she does not have cartilage hair hypoplasia (Meredith Eaton has pseudoachondroplasia).
Other mistake: House and Wilson are in the Mens room, and there is a tampon/sanitary pad dispenser. (00:21:30)
Answer: You have the right episode. The big deal at the end about the letters on the pills was to show that Brandon had the wrong pills all along. House was smiling because he was right.
MoonFaery ★