First, write down your feelings. If you don't like writing, keep a journal anyway. Write down every thought, every emotion, ECT. If drawing or writing peoms bring out your inner feelings do that too. Expressing yourself is a good thing. Look for your symptoms. Symptoms of depression include: Sadness, lack of interest in activities you once enjoyed, frequent crying spells, thoughts of suicide or death, decreased or increased appetite, lack of sleep or increased tiredness, a feeling of hopelessness or worthlessness, poor self image, and self hatrid.
Step2
Depression hurts...phsicically too!
Think of ways why you might be depressed. Was it a past tradgedy? A recent happening? Sometimes, its best to see a counselor to help you get through stuff. See a doctor. they can give you a test to test for depression and maybe prescibe a medication to lesson the symptoms. Mood swings can also be related to Bipolar Disorder or ADHD. They'll also test for these.
Step3
You CAN get your life back on track!:)
I recommend seeing a counselor and a doctor before your depression can worsen. Who wants to live a life of pain and guilt? You can be free!