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Greetings of the day
Its most likely that the swelling you noticed is post-auricular Lymph
Its quite common to see small post auricular lymph node in the neck and behind the ear because of hyperemia
because of sweating.
There is no cause for concern.
In case you need any further assistance, will be glad to assist you.
Wishing you happy and healthy life
Dr T Shobha Deepak