It is important that you help your child name his feelings (happy, sad, frustrated) and express himself in a positive way. Your child’s ability to express how he is feeling in a positive or appropriate way will have an impact on how relationships are formed with peers, family, and other people in his environment.
Toddlers haven’t yet learned how to control their emotions, and mood swings can be alarmingly rapid and intense. But they are also—thankfully—short-lived, moving from screaming in frustration to smiling and playing within seconds. Staying calm, helping them with the source of frustration, and using distraction techniques (“Oh, look, a red leaf!”) will help them. Don’t expect miracles though— plenty of five year olds still have difficulty controlling their emotions.