Head CT scan results - headaches

I am a 74 year old female.  Headaches started 2 months ago with pain in top of head and ache down sides of face with pressure behind ears.  Dental, eyes, and ears examined and eliminated as problem.  No relief with nsaids.  Primary care doc ordered CT scan without contrast.  

Results:  No evidence of hemorrhage, mass, edema or extra-axial fluid collections.  Paranasal sinuses and mastoids clear as imaged.  Bony structures intact.  Ventricles normal in size and position.

Cortical sulci, basal cisterns, and cerebellar folia mildly prominent (what does this mean?); small lucency in left parietal lobe is probably partial volume averaging with a prominent sulcus (what does this mean?).

Any suggestions as to finding source of headaches?