In Chapter Four, Conner notices that Alex is acting strangely.... how so?

In Chapter 4, Conner notices that something strange is going on with Alex as she is not her usual chipper self. Conner finds it particularly surprising that she asks him to borrow his pencils. He confronts her one night because of the loud humming that wakes him up, but Alex lies and says that it was a bee that had come into the house. The next day in class, Alex is inattentive and fails to answer their teacher's questions.