Mental illness is a strange and difficult condition to understand.
Those suffering from it are often the best at diagnosing themselves, with help from trusted, more mature friends who also suffer from mental distress.
Psychiatric assistance can help. However, given current diagnostic methods (effectively a series of tick-boxes defining an increasing range of human variation) the chances of a correct psychiatric diagnosis is slim.
Supposed help from ignorant family and friends is not only unhelpful, but actually highly dangerous, and can cause suicides, self-harm and unnecessary admissions to hospital.