Desiree Lindsey, 28, kept getting sick during her period. The Las Vegas fashion entrepreneur's nausea had become so crippling at work that she was unable to hold down food and would spend most of the time in the bathroom.

"It got to the point where I'd have pillows, step stools, my laptop and chargers with me in the bathroom, just in case," she said.

In addition to abdominal cramping, intense pain during sex can occur when endometrial tissue in the uterus is irritated during penetration. This is the reality of endometriosis, a disease that doctors confirmed Lindsey had in 2016. The condition—which affects approximately 6 million people in the United States—causes tissue to grow outside the uterus, where it implants onto organs in the abdomen. Lindsey said even before her official diagnosis, sex had always been painful for her. The same year she was diagnosed, she underwent a laparoscopy, a procedure that examines the pelvic organs and removes endometrial scar tissue with minor excisions.