If you have cracks or other breaks in your skin, rinse your nipples with a mix of mild salt water (1 tsp salt to 1 gallon water). (breastmilkcounts.com)
They don't involve visible breaks in the skin or broken bones and are typically localized in the muscles of the shoulders, neck, and back. (bhattlawgroup.com)
It is most common in children under the age of 6 and begins when bacteria get into the skin after a small break in the skin like a scratch or insect bites. (floatinghospital.org)