Clinton Left 9/11 memorial due to pneumonia and Cancels West Coast trip

Hillary Clinton has called off plans to visit the West Coast on Monday and Tuesday following her 'medical episode' at the 9/11 memorial ceremony.

Her doctor revealed that the 68-year-old has pneumonia - hours after a video showed her collapsing into the arms of her Secret Service agents after being rushed from the memorial service at the World Trade Center. 

Dr Lisa R Bardack said Sunday evening that Clinton had become overheated and dehydrated at the event in lower Manhattan. 

Bardack said Clinton is now 'recovering nicely' at her home in Chappaqua, New York.

The Democratic nominee was scheduled to attend fundraisers on Monday and Tuesday in California, and tape an episode of Ellen DeGeneres' talk show. 

Clinton is now holed up in her upstate New York home after a bystander recorded her losing her balance, slumping at the knees and being held up by her aides while waiting to get in a minivan.

Her campaign had earlier blamed 'overheating' for the episode - which saw her rushed away from the ceremony at Ground Zero and back to Chelsea's apartment. 

Her press pool was not informed for 90 minutes of her whereabouts or given an explanation for the abrupt departure. 

At the time the temperature was around 80 degrees and the humidity was low. 

Earlier on Sunday, Bardack said that Clinton 'has been experiencing a cough related to allergies'.

On Friday, during follow up evaluation of her prolonged cough, she was diagnosed with pneumonia. 

Bardack said Clinton was put on antibiotics, and advised to rest and modify her schedule. 

'While at this morning's event, she became overheated and dehydrated. I have just examined her and she is now re-hydrated and recovering nicely.'

Clinton's collapse adds to growing fears for her health, which began mounting on Labor Day when she broke out in a coughing fit during a speech in Ohio. 

It now seems that cough has developed into pneumonia, according to Bardack's statement.

Katie Packer, a GOP strategist, told the Los Angeles Times that the incident will increase attention on the health of both Clinton and Trump, 70.

'This is the kind of thing that voters have a right to understand before they cast a vote,' she said. 

'But Trump and Hillary are elderly. They are obligated to release full medical records and full tax returns to the American people. And the media, party leaders and American people should settle for nothing less.'