My right nipple has been sore since i stopped breastfeeding three months ago. what can it be?

Mastitis?: Mastitis is a breast inflammation usually caused by infection. Mild cases may occur with breast feeding or around the time of breast feeding. The simple build up of breast milk and no relief of the pressure since feedings stopped may also cause discomfort under the nipple. Warm compresses may help, medications may be needed such as anti-inflammatories or antibiotics. Best to see you Dr.