He could also ask any one of the other people in the area who know what is going on, such as Archy, the staff of the Harbringer, Drake, Myrn, or Natalie.
And to be fair Archy really is not sure as to whether or not the castle has doctors right now as things have been kinda whack.
Even if they may not personally know Chaos they can still explain stuff.
EDIT:I don't think there's anyone who knows Chaos in the castle, either. Zypher, Diana, and Spike are in there, and while Westy might know something, she's weird and isn't going to be saying anything.