Its definitely infected.
You need to stop touching it.
Have your doctor have a look at it, clean it out with alcohol
and give you some anti biotics if you can.
And if you need to touch it, to adjust it or whatever, please
wash your hands and fingernails thoroughly. Wipe dry hands
and spray, wipe, splash some alcohols before you even touch your
ears.
Careful when you shower and change your pillowcase and wash your
pillow regularly.
Keep your hair off that ear.
If possible change out that stud to gold or surgical steel stud,
cos you may have been allergic to the plastic.
And stay away from prawns, seafood for another two weeks till it
heels. (I know its old wives tales but lets just be safe, not
sorry.)