https://psychologyfoundation.org/Content/Professional__Educators__Social_Service__Health/Children__4-13_/Stress_Lessons.aspx
When you’re a pre-teen or teenager you can have mood swings—that’s when a person’s feelings change quickly and might feel very intense—are a normal part of puberty. You might feel moody, crabby or even suddenly want to cry and then feel fine or happy. These mood swings are often caused by hormones, and they are totally normal while you’re going through puberty, sometimes it’s called “teen angst”.