R.M.
Hi B.,
What is happening in your life and home currently? Is this a new behavior, or has he always had difficulties expressing himself? I'm a parent coach who helps with behavioral issues. More often than not, when a young child is acting like this they do have a problem they cannot express. Boys have a harder time with language skills and often act more aggressively than girls do.
Start by thinking about any changes in your life lately and work from there. Even small changes to you can be a huge issue for your son.
When you see a fit, help him gain control and then talk with him about the situation.
I hope you can figure it out.
R. Magby