Kelly is among a growing number of doctors who are starting to use what scientists are learning about our microbiomes to help prevent, diagnose, and treat many illnesses. For Iverson, she proposed something that may sound pretty radical — what doctors call a fecal transplant.

"It's really almost like an organ transplant," Kelly says. "You're taking this whole community of microorganisms from one person, [and] transplanting them into another person. Then these things ... take root, colonize and kind of restore that balance."

Iverson says she initially found the idea repulsive. But she felt so desperate that she agreed to try it.

"I was scared to death, honey," Iverson says. "I'm an old lady. I've got one foot in the grave and the other on the banana peel."

The procedure turned out to be really easy. And it worked — virtually overnight. "It stopped," Iverson says. "Right away. I'm feeling good now. I'm feeling great."