As a first-time mother, 35-year-old Stephanie Cobb expected to feel exhausted after the birth of her daughter, Eloise, in early 2019. But six months later, she noticed other concerning symptoms. She experienced trouble breastfeeding, developed a leathery texture and bruise-like rash on her left breast, and felt a shooting, needle-like pain in the same breast. 

Stephanie was initially diagnosed with mastitis. After seeing multiple...