Hi there,
Erythema (redness) and swelling are possible and early warning signs of a skin infection, given your recent ear piercing. Other signs and symptoms of a skin or soft tissue infection may include warmth, pain, especially pain on pressure/touching and presence of any discharge from the piercing site.
I highly suggest that you see your general practitioner to review this piercing for possible infection and to ensure other important structures in this area e.g. ear cartilage tissue is not damaged.
Best regards,
Dr. Joanna Chan