Mood swings, anger out bursts, crying spells, disturbed sleep and appetite, negative thoughts, low mood and loss of interest are classical signs of Depression. Depression is a disorder involving brain circuitry dysfunction. Please go to a good psychiatrist near your place and start treatment. The psychiatrist may give you psychotherapy, or medicine or both. Don't worry it is a very common and treatable condition. Early and completely treatment ensures complete recovery. In the mean while it may help to exercise and socialize . These however, can't replace treatment.