Thanks for the additional information.
It sounds like one of two things. Either one, she had something happen to her that she is not telling you about like some type of trauma, or two, she is more upset about the divorce than she is letting on.
Has she talked with you about her feelings? Does she seem ok in other areas of her life like grades?
It sounds like her doctor has a good relationship with her, but not referring her for a therapeutic eval is not a good idea. She needs to be seen to determine what is going on. If you have to be referred through her doctor, you may want to consider asking for a second opinion and talking to the new doctor about your concerns. If you do not need to have her doctor do a referral, then you can find a therapist by searching on line at www.find-a-therapist.com. If you attend church, you may be able to talk with your pastor about a referral.
Approach your daughter about this by telling her how much you love her. Let her know you want to talk with her about how she is doing. Use a neutral, non judgmental tone of voice. Let her talk about anything. If she starts off by talking about something that seems unimportant, it might be her way of testing how you react to her. So just let her talk. Even if you do not get very far the first conversation, let it go. It may take a while for her to build up to telling you about whatever is bothering her.
Right now, she is holding her feelings in and covering them with overeating, not caring for herself and isolating herself. With those kinds of symptoms, there is something going on for her that is traumatizing. With some patience and care, she will eventually be able to let her feelings out and get help.
I hope this has helped you,