Depression is a combination for physical and psychological factors. A psychiatrist/ psychologist can be helpful. On a psychological level depression is triggered due to negative view about self, others and future. There can be constant why me feeling that needs to be worked upon.
Next Steps
See a psychologist also trained in CBT
Health Tips
A combination of meds and therapy may be required. Learning skill to manage thoughts can help you life long and keep yourself upgraded with new ways of dealing these thoughts.