"She would throw up in the bushes on the way to class," said Lynne Bussey, Robertson's mother. "Sometimes she would have to run out the door in the middle of class."
Initially, some thought Robertson, who was 18 at the time, was hung over from a night of heavy drinking. Others believed she was bulimic. And although Robertson claimed her vomiting episodes would come without warning, many did not believe her mystery illness, she said. Teachers warned Robertson that excessive absences from class put her at risk of failing.
"I've had to drop classes because [my illness] has been too overwhelming," Robertson said.
Many doctors diagnosed Robertson with the stomach flu or food poisoning, Bussey said. Yet, Robertson's symptoms persisted for two years until she was diagnosed with CVS.
Unlike with bulimia, which is a cycle of binge eating followed by purging, those with CVS have repeated episodes of vomiting that can begin and continue on an empty stomach. Also, CVS episodes are induced by overwhelming nausea, while individuals with bulimia often vomit without feeling nauseated.
Robertson has been hospitalized more than 60 times in the last decade. Like clockwork, Robertson woke up with a headache or nausea; oftentimes she started her day after she vomits. Her symptoms eased in the evening, but recurred early the following morning.
Bussey said she has connected with at least 15 others in Butte County who have the disease and also claim that they are not believed.
Dr. David Fleisher, an associate professor of children's health at the University of Missouri who has treated Robinson and more than 400 other patients with CVS, said he understands why many with the disorder are met with skepticism from others -- doctors included. The primary reason, he said, is that many physicians may not have heard of the disease.
"With functional disorders like CVS, the only way to diagnose it is to get a patient's history of symptoms," said Fleisher. "Not many physicians know the clinical pattern of CVS, so it's hard for patients to get the recognition or care they need."
CVS is often mistaken for other disorders including urinary tract infection, appendicitis and brain tumors seen in MRI scans, Fleisher wrote in a 1993 article in the Journal of Pediatric Gastroenterology and Nutrition.
In a 2002 issue of Contemporary Pediatrics, Dr. B.U.K. Li, director of the Cyclic Vomiting Program at Children's Hospital in Milwaukee, Wis., and one of the world's leading experts on CVS, blamed the on-again, off-again symptoms for difficulties in understanding the disease.
"Between episodes, the child with CVS is asymptomatic and appears so normal that the history of repetitive bouts of relentless vomiting and dehydration can be difficult to believe," he wrote.
According to Fleisher, some behaviors by individuals with CVS during an episode may also mislead doctors.
Bussey said when her daughter has nothing left in her stomach to vomit, she drinks water to induce vomiting, which can make her feel better, which, according to Fleisher, is an action some doctors may interpret as bulimia. Otherwise, the violent reflux and bile may cause her daughter to burn her esophagus and stomach lining, Bussey said.
At times, an attack can send Robertson into a state of conscious coma. Robertson can understand what is going on around her, but is unable to respond to others.