The Democratic Party presidential candidate, Hillary Clinton, has cancelled a campaign trip to California because of sickness. A spokesman made the announcement Sunday. Earlier that day, Clinton left early from a ceremony in New York marking the 15th anniversary of the September 11 terror attack. A video shows her stumble before guards help her into her vehicle. Clinton’s doctor said she had become overheated and dehydrated at the event. He said she is recovering well. Her campaign said the doctor had examined her on Friday and reported she had pneumonia. The diagnosis was not made public until Sunday. She was treated with antibiotics, advised to cut back on her appearances and to get rest. Clinton’s now-canceled trip to California was to include money-raising events and a speech about the economy.