area behind the ear is mastoid. and the history you provided coincides with mastoiditis
. had you a recent episode of sore throat
of ear pain
or hearing disturbances or buzzing in the ear or any vertigo and dizziness?
hurting with the movement of neck indicates it might have become a little abscess or some complication of mastoiditis like bezoalds abscess etc.
Do a simple plain xray film and blood count and audiometry
and consult an ear nose throat speciality nearby as you might need a little intervention in this regard.
Dr Shafi Ullah Khan