Xin Zemin and Zhao Huan had rushed back immediately after learning about Xiu's condition. Well, technically, Xin Zemin wasn't able to grasp the situation at all over the phone call. He only heard that his daughter cried and fainted. That was enough to put him in a frenzy.
As soon as he came back, he asked his brother, "What happened?"
Xin Zimen was rubbing his forehead as he replied, "If I knew what happened, I wouldn't be so disturbed right now."
That was the main point here. Zimen himself didn't have a single clue about what went wrong. He clearly could see that Xiu was happily talking to him after her sessions. She even joked around making him laugh out. And he knew she wasn't faking it at that time but then suddenly something went wrong.