Sara, I'm sorry to hear that you are experiencing this rollercoaster of emotions. If you don't mind me asking, how old are you? A lot of mental disorders tend to present themselves in the latter teen years and can really change someone from who they were to someone completely different. I was a reasonable calm kid and got hit with it when I was 16. I was later diagnosed bipolar. If you are really concerned about this, I would suggest speaking to a therapist, or doc about your emotions and maybe you can get some answers as to why you are going through this. Once you know why, you can better learn to cope and manage your emotions and stresses.