What does this mean?

My son is 14 months old and since he was about 6 months old I believe, he bangs his head. At first it was only now and then, so I wasn’t concerned. But for the past month he bangs his head on the pillow every day before naps or before bed time.

He also sometimes has a head tic where he shakes his head repeatedly and so I’m not sure what all of this means.

Does anyone know if this is normal or if this is a bad sign of something serious?

He will be going to his check up next month, but idk what to think right now.