Hello, Since you have a job that makes you sweat a lot, make sure that you have spare clothes to change whenever you feel uncomfortable. You need to have a soft towel as well. From your symptom, it seems that you have nipple fissure (rash, chafing, crusting of the skin, cracked nipple) & that is causing you stinging pain. You have sensitive skin, when you are sweating do not wipe yourself harshly. Nipples are delicate areas with high blood supply, don t make them crack. You should have showers twice daily. Take care of your hygiene. You can apply Neosporin ointment in the area affected. You can take Acetaminophen for relief from pain orally when needed. However, if it shows no signs of improvement you are suggested to visit a GP, get physically examined to rule out gynecomastia or male breast cancer. Stay away from addictions & drug abuse. Wear loose-fitting soft cotton clothes. Hope I have answered your query. Let me know if I can assist you further. Regards, Dr. Nupur K, General & Family Physician