node swellings behind and around the ear can be pretty common and are mostly due to infection in the scalp
or mouth or external ear. Sore throat
and toothache can lead to enlargement of these lymph nodes. Therefore you need to get evaluated by your GP regarding the requirement of antibiotics since you have a sore one. Usually they do not signify something more serious in the first place unless you have a history which can cause chronic lymph node swellings.