I used to do that when I was a teenager. It was because I didn't have the ability to cope with bipolar moods and being a teen so, I'd cut myself to distract myself from the emotional pain I was in. I also had some strange probably psychotic thoughts back then that contributed to that behavior. I'm sure that doesn't apply to your daughter. The whole strange thinking that came up is unusual for your typical cutter. I have scars all over my arms and legs but, grew out of it by the time I was 21 with one exception when I was pretty much psychotic on Zoloft.

Now the thought makes no sense to me and I have no urge to inflict pain on myself. It hurts! Of course, now things are a lot less intense. I have answers to what is going on and I have coping skills.

You're doing at least one thing right though! Your daughter actually came to you about it. Even now, years later and I finally told my parents about the bipolar diagnosis, I'd never tell them that I used to do that. We aren't the type of family that talks about emotions. That's for normal people, who ever they are, and families on tv.

Does your daughter know why she is doing it?

Edit: read another post of yours and see you're a church goer. No judgement there. My experience though is that you want to keep this behavior away from "Christian counsellors". The whole your body is the lord's temple approach really does not help someone dealing with self harm. There is already a lot of shame involved in the motivations to do it.