Eye movement & pain
A most difficult question!.
Many causes can be found. Only a thorough exam can bring light to this very subjective symptom. Most likely eye
muscle related: thyroid myopathy
, orbital myositis
, residual sign of trauma that may involve the trochlea where the superior oblique "hooks", superior oblique myokymia
of unknown cause and plain eye tiredness (asthenopia
), more history is needed.