Welcome to the forum. I can understand your concern because nipple pain in males is very uncommon but
possible. I cannot precisely confirm a diagnosis without examination but it can be due to different reasons.
It depends on whether the pain is in the nipple itself, the tissue beneath or the ribs. If it is in the tissue
under the nipple you may have a chronic infection which can result in a cyst. These are often tender and
painful. Pain at the nipple itself may be from infection or constant rubbing against clothes which can cause
chafing. Sometimes if there is a history of any arthritis, the ribs can be painful where they join the breast
bone. Pressing on the rib through the nipple will trigger this pain. Even males can have fibroadenomas which
are benign lumps but may sometimes present with breast or nipple pain. I suggest you to get it evaluated from
a physician. In the meantime apply warm compresses and take some anti-inflammatory pain relievers like
Ibuprofen( if you are not allergic to this drug) or acetaminophen after consulting your doctor. If along with
the nipple pain there are other symptoms skin dimpling or puckering, redness or scaling of the nipple or
breast skin or some breast discharge, then breast malignancy has to be ruled out and needs to be evaluated
right away. I hope it helps. Take care and please do keep me posted in case you have any additional doubts.