Why my nipple pain?

Nipple pain can be a real bother, mate. Often, it’s simple stuff. Think friction from a shirt, especially during exercise. That's a classic cause of chafing. Hormonal changes are another big one. Your cycle, pregnancy, or menopause can all be culprits. It could also be skin irritation from new soaps or even eczema. Less often, it might signal an infection or another underlying issue. Honestly, your best bet is to have a chat with your GP. They can properly check it out and give you some peace of mind. Don't rely on online forums for a diagnosis.