A lump under the ear might indicate a swollen llymph node. Swollen lymph nodes can be due to many causes including infections, autoimmune diseases, fungal and bacterial infections and lymphoma (cancer). You can read about the lymphatic system in the dog here:
Now it could be due to a puncture wound that the pup sustained at birth. Often a mother will inadvertently nip the pup while trying to free them from the sac. If it is a first time mom, they sometimes are anxious and bite a little too hard and create a wound on the pup that often is not seen. The outer skin heals but bacteria is trapped under the skin and an abscess develops. You can read about here:
You will likely need to have the pup seen by your vet. Your vet can determine if it is a lymph node swollen or an abscess. If an abscess, the vet can drain the abscess and prescribe antibiotics to help clear up the infection.
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