She’d go to work as a physician assistant, come home at 3:30 p.m., and lie flat on her back through the evening. Weekends were the same. She’d gained weight, was losing hair, felt depressed, and couldn’t think clearly.

“Literally, I did not get out of bed,” McPherson told Fortune. “My life was a constant chase of, well, I have to rest enough to recover for the day and rest enough to prepare for tomorrow.”

So she did all she knew to do: go back to her doctor and ask to adjust her medication. He ran a single lab, told her the thyroid was fine, and suggested she eat less and exercise more. As she recalled, he actually wanted to reduce her dose, and handed her a cholesterol prescription for a problem her thyroid was quietly creating.

“I cried in the car on the way home and thought: ‘If he takes anything else away from me, I will not be a functioning member of society,’” McPherson said.

That drive home from the doctor’s office became the origin story for Modern Thyroid Clinic, the Bee Cave, Texas-based telehealth practice McPherson, a physician assistant, founded and now runs as CEO. It started as a super small operation in which McPherson was the clinician, the scheduler, and the medical assistant, and she paid a single phone answerer $2 per call.