1 breast very sore. feels like whn i breastfed 3 yr ago. no idea why but very sore deep inside areola area. no lumps & i rarely drnk caffeine. ideas?

Cyst: Cysts and fibroadenomas (benign tumors) are the most common cause of unilateral breast pain. I would see your doctor for a breast exam soon. They will likely order an ultrasound and/or mammogram to determine what the cause is. Sometimes there is no cause found. In those cases ibuprofen and evening primrose oil (pills) can be somewhat helpful.