Give her the benefit of the doubt, maybe she is sick. Also pay attention to her behavior when you talk to her 1 on 1 in the future. Does she actually like to engage in conversation? Or does she just answer your questions with one word and seem totally disinterested in speaking to you.
follow her home, give her some medicinal herbs, if someone else comes to the door, ask if shes sick, if they say no, then she lied (obviously) and then you throw rocks at her window