It's good to see that you're so concerned about your friend.
So first we suggest that you talk to her parents or close friends if you know them. Learn about any previous experience which may have led to her this behavior.
Also, if will be of great help if anyone can directly talk to her. Maybe there is something troubling her which she is unable to share.
Also, this behavior problem could also be due to this sudden change. Leaving school and joining College is a drastic change of life. Sometimes we are not completely able to adjust to it. Maybe she hasn't got good company. Our peers affect us deeply.
So, we hope that you or someone talk to her and are able to find the root of the problem. You can contact us again also.
All the best :)