In one of the picks below, it says who told Amber about House's syphillis, he had syphillis? When do you find that out?

Season 4 episode 13
Called "No More Mr Nice Guy"
House want to mess with the team so he left somebody eles blood in the lab but put his name on it. He then told Wilson what he was doing and he told Amber.
I hope that make sence to you, it was good episode you should watch it :)