Most common cause can be hypersensitivity
to the metal you are wearing. It sometimes happens that you are using same material on both sides and problem occurs on one side. Use antibiotic and steroid
combination ointment for few days after removing the ear ring. Always use pure metal and not the artificial one. Other reason for unilateral problem can be the position of prick. If it is touching the perichondrium of pinna cartilage
(high prick on lobule), it can cause some problem. Regards.