"We have one or two days left to help these people. After that they will start dying en masse," Vian Dakhil told AFP.
"If we cannot give them hope now -- the (Kurdish) peshmerga, the United Nations, the government, anybody -- their morale will collapse completely and they will die," she warned.
Thousands of Yazidis, a Kurdish-speaking minority following an ancient faith rooted in Zoroastrianism, fled their homes a week ago when Islamic State (IS) militants attacked the town of Sinjar.
The Yazidis, dubbed "devil worshippers" by IS militants because of their unorthodox blend of beliefs and practices, are a small and closed community, one of Iraq's most vulnerable minorities.
US President Barack Obama sent warplanes back over Iraq for the first time in three years this week in part to avert what he said was a possible impending genocide.
American cargo planes have been dropping supplies on the Sinjar mountain to help the displaced, who have survived by hiding in old cave dwellings, seeking out natural springs and hunting small animals.
