TweetGood on you for posting this and seeking out solutions for your daughter. This is an urgent situation and my heart goes out to you guys.
Gosh, teen depression appears to be an epidemic. There was a recent cover on Time magazine about this very issue.
Oftentimes is situational. Its due to some circumstance that they feel they cant control. I am fearful of the influence of the pharmaceutical industry and doctors seeing these problems as a chemical problem. Typically thats the first thing they want to do is get the kids on a prescription med. I dont know what the statistics are for those drugs but I doubt they are doing kids any good. I can understand though how a parent would resort to anything to help their child and people trust their doctor.
Its hard for kids to get perspective at that age and every event can seem cataclysmic to them. You get dumped by your girlfriend/boyfriend and its the end of life as you know it. She an excellent student. Possibly she is overthinking some things. Smart and introspective people can sometimes think themselves into feeling low.
Maybe counseling could help her. Good that you have open communication.
Keep seeking answers and hopefully some people on here with more experience than me can offer some information . Good luck