What is the cause of nipples pain

What is the cause of nipples pain.
The person is not pregnant, not menstruating, not breastfeeding.

sir pls I think u know the answer before posted can you pls tell us the cause of it?

Be specific. nipple of one breast or all breast? If its only one breast observe other condition may there any sore or swelling this can be likely infection or a certain tumor( cancer). But if its all breast nipple wearing tightly clothes can be the cause.

Please what about hot sensation or pain on the breast when the person is neither pregnant nor lactating nor active in sex.

The top breast nipples is cracking or not we give you finally answers?