Psychological problem. At the same time.

Loss of appetite since more than a month. I always feel tired and inactive to do some work. Either it's too difficult to fall asleep or I sleep for more time. Lack of concentration and remembrance. Lack of interest on doing things. I either be more active sometimes and suddenly I become inactive the very next. I get into moods where I feel very speeded up or irritable. For no obvious reason I sometimes become very angry or hostile. My self-confidence ranges from GREAT self-doubt to equally great overconfidence. At times I am much interested in being with people and at other times (mostly) I just want to be left alone with my thoughts. Sometimes I am mentally dull and at other times I think creatively. There have been times where I felt both high (elated) and low (sad) at the same time.