Hello Friend, Good that you are seeking a help here. Overthinking of any past or future or any unpleasant incident cause depression in your mind. This inturn leads to behavioral changes like anger, disturbed sleep or excess sleep, lack of interest, laziness, weight gain or loss and many more.
So don't hesitate to consult a mental health professional to ventilate your emotions and feelings first . In this process you will be able to isolate the root cause for depression and suitable solutions to overcome.
Next Steps
Consult a psychologists directly or online.