My immediate interpretation was this girl wants to have sex with him and she's anxious to get him alone. He'd like to let her, but he knows it's not right (she could be his friend's girlfriend or something...) so he fears doing anything ("moving") to make her think he's trying to make a pass for her. Maybe when he says "itch" he's not saying she's annoying but that she's something he feels he needs to scratch or that she's under his skin despite his efforts to not think about her. The Police's "Don't Stand So Close To Me" comes to mind--obviously without the teacher/student relationship, but the idea of wanting something you can't have and struggling to resist.
My immediate interpretation was this girl wants to have sex with him and she's anxious to get him alone. He'd like to let her, but he knows it's not right (she could be his friend's girlfriend or something...) so he fears doing anything ("moving") to make her think he's trying to make a pass for her. Maybe when he says "itch" he's not saying she's annoying but that she's something he feels he needs to scratch or that she's under his skin despite his efforts to not think about her. The Police's "Don't Stand So Close To Me" comes to mind--obviously without the teacher/student relationship, but the idea of wanting something you can't have and struggling to resist.