I'll not forget the best words of wisdom by my gram as my youngest started a spell, she reminded me that it's important that I let him feel his feelings. He was about 2 at that time.
Of course, now I'm living an era of hormonal changes so it's rather trying to embrace their mood changes.
I don't know if fortunately or unfortunately with their closeness in age, but I'm beginning to see a light at the end of the tunnel through my oldest as his own moods are reaching what seems to be a plateau at 15.