Uncountable Emotions

I don’t understand my emotions. Maybe it's something every teen face, constant mood swings. I feel sad all of a sudden, I cry for hours, unable to stop. Although I have no idea why I’m crying so much. The sadness turns into sudden hate and jealousy. I don’t understand why. I start hitting the wall or doing something to just reduce all this anger and sadness. Sometimes I end up going back to happy. I don’t understand my own emotions and it irritates me.