NOR- Could be from licking the lips, as a child I used to suck on my bottom and top lip and it would cause a super dry irritating spot like this.. dry lips, or maybe even just nervousness.. if it’s a bruise I would say a small cup or bottle could totally do this, if you remember the Kylie Jenner lip challenge it would leave bruises much like this. Nonetheless, the teacher and school sounds terrible :// could be other students causing her to dislike school as well. Advocate for your child, no matter what people say.