5 Year Old Child - Discovered Small lump on Back of Head

I just discovered a small lump on the back of my 5 year old daughters
head that's about the size of a bean or a very large raisin. It's hard
and non-moveable. It's parallel to the ear towards the back/bottom/left
of her head. Almost feels like part of her head but it definitely
protruding and unlike the other parts of her head. We never noticed
this before.

We first thought this may be the result of her bumping her head on a
table recently although we do not remember an exact location of where
she hit, nor did she complain. That was about a week ago.

She says the bump doesn't hurt, then she say it does. You know kids.
She is otherwise acting normally - eating, drinking, playing....nothing
nuerological of concen. No red marks in the location of the protrusion.
It just looks like skin covered by hair.

Has anyone seen this on the back of their child's head, or anyone?
Could this be a normal development abnormality?