Recent research indicates stress can affect some aspects of memory & certainly stress can cause headaches. Of course there could be other physical causes which I suggest should be checked out with a medical check-up if she has not had one with a GP (local doctor) already. I wonder if anything in particular has happened which led to these symptoms or if they emerged over time independently of any events in her life. I also wonder about her sleep & appetite. The good news is that therapy can address depression, fear, crying, concentration at school and other symptoms. New brain cells can be made in just 6 seconds and that is a wonderfully uplifting fact which enhances the knowledge that it is possible for most people to positively change their psychological well-being. I suggest that as well as being supportive and empathetic that you encourage her to see a psychotherapist. In addition to her having one to one work it might be that some joint work involving you would also be helpful.