help? does my four year old have anxiety?

He's a really smart boy, he wants everything done his way, in school he's doing well, his teacher tells me he gets really angry and explodes by screaming and yelling at his peers when they won't play with him, he usually gets very angry and his the children that refuse to clean up during clean up time! He's been yelling at me and his little 2 year old brother and father when I say yelling he is boyond angry he recently started doing a weird movement with his arm where he stretches it and a little with his neck where he also stretches it he does this at random times throughout the day, he doesn't do it when he first Wakes up or when he sleeps?

I want to think that he hurt his arm cause he had complained About pain when this began about 3 weeks ago but the hasn't complained about pain now but his arm does pop every once in a while!

Thank you