Before the anti-med people chime in:
The meds, especially the SSRI class, help a lot of people and can save a life.
They DO increase the danger of suicide for some people in the short run, which is why their use, especially in a child, should always be managed by a competent therapist.
And agree completely about social media. There is a ton of literature, with a lot more in the pipeline, about the role of social media in causing, and especially worsening, child and adolescent depression.
In this case the kid seems like they may have bipolar depression or some other mood disorder. In those cases SSRI class drugs often make kids dramatically sicker, since they induce hypomanic mixed states and other very undesirable situations.
General practitioners can easily misdiagnose other serious mood disorders in adolescents as depression, since the symptom they see from the kid is depression and the other symptoms of, for example bipolar disorder, are harder to detect in adolescents. For example, rapidly shifting moods indicate a different kind of disorder - and suggest not using SSRI anti-depressants. But teenagers tend to have rapidly shifting moods anyway, so mild examples of that don't get recognized except by specialists.
Medications are important, but for the kind of problem described by the poster you need careful intervention by a specialist in adolescent psychiatry.