Hello and Welcome to ‘Ask A Doctor’ service. I have reviewed your query and here is my advice. Possible causes are 1. Friction of clothing associated with running or exercise is one of the most common causes of nipple pain in men. Aptly named ‘runner’s nipple,’ the condition speaks for itself. 2. I also see this in patients who engage in exercises with lots of vertical and/or horizontal movements including soccer, rugby, plyometrics, boxing, as well as Zumba occasionally. 3. Also it may be underlying cause seen in Paget s disease or diabetes or Infection etc. Wear synthetic fabrics such as Dri-Fit hug the body closely, reducing the chance of friction occurring in the first place. Please consult your physician, he will examine and treat you accordingly. Take care.