Hi You are around 16yrs, Your mood swings may be due to life events stress. So don't worry, Focus on your goal and move on.

Bipolar disorder, is a brain disorder that causes unusual shifts in mood, energy, activity levels, and the ability to carry out day-to-day tasks. Bipolar disorder often develops in a person's late teens or early adult years. . Some people have their first symptoms during childhood, while others may develop symptoms late in life.  You can visit a psychologist or a psychiatrist and talk to them about your symptoms and your background ...