Don't try to analyze head bumps. There is no valid purpose. It happened. It is history. Move on with life. A backhand does not have much mass....That is all I will say.

Bone and skin bruises can be painful. That pain has no bearing on the brain.

You listing of all the details, weight, her weight lifting, etc. is anxiety trying to justify a reason to be upset.

Move on. Ice your face to help with bone or skin bruises if needed. Aspirin, Tylenol, or Ibuprofen for head ache.