It is not necessary to go to a tattoo parlor for a third ear piercing. However, in terms of sterile equipment and experienced piercing technicians, tattoo parlors are a good choice.
Ear piercing, no matter if it's the first or third, can be done at a jewelry store, a doctor's office, the local mall, a tattoo parlor or at home. Where the ear piercing is done is not as important as how it is done, with sterile equipment and procedures being the key. Tattoo parlors follow state regulations for cleanliness, and use disposable needles, whereas mall kiosks and jewelry stores use piercing guns that cannot be completely sterilized.