A question for all mothers !

So I’m a bit concerned because my 2 year old always always goes to hit his head whether he’s in bed, or in the living room he’ll find a wall or a floor to hit the front of his head and if he’s sitting down he’ll hit the back of his head when he doesn’t get his way or we say NO. He hits it so hard to the point where it’s starting to worry me. My mom suggests I take him to therapy. Am I doing something wrong? I don’t know the right way to teach him how to express his feelings or frustrations without him having to hurt himself. Have any of you gone through this? I’m a first time parent so I just don’t know how to get him to stop or if this is normal?