Hillary Clinton is seen standing on a curb near the World Trade Center when she appeared to lose her balance on Sunday, September 11, 2016.

US Democratic presidential nominee Hillary Clinton says she is "feeling fine" a day after she was forced to abruptly leave a 9/11 memorial in New York due to an apparent medical episode.
"I'm feeling fine and getting better," Clinton tweeted on Monday, signing her message with the "H" that indicates she personally wrote it.
"Like anyone who's ever been home sick from work, I'm just anxious to get back out there. See you on the trail soon," she said.
The candidate’s physician, Dr. Lisa Bardack said that she was diagnosed with pneumonia on Friday.
A video of the incident emerged on Sunday, showing a seemingly fainting Clinton stumbling on the sidewalk while her security detail took her into a van and drove the former secretary of state to her daughter's house.
Clinton told CNN on Monday that she "felt dizzy” and lost her balance, but added that after getting into the van and drinking some water, she “immediately started feeling better." 
Clinton also said she would return to campaigning "in the next couple of days.”
“I just want to get this over and done with and get back on the trail as soon as possible," she stated.

Hillary Clinton is seen wearing sunglasses as she arrived in New York on Sunday. (AFP)

The incident on Sunday meant a chance for her Republican rival Donald Trump to question her fitness to become president.
On Monday, Trump commented on Clinton’s pneumonia "diagnosis", saying “something’s going on” with her.
"Like you, I see what I see...Something's going on but I just hope she gets well and gets back on the trail and we'll be seeing her at the debate."
In case a candidate is not able to finish a political race, there is no guidance in the US Constitution about what can be done.
Article two, section seven of the Democratic Party bylaws stipulates that "a special meeting to fill a vacancy on the National ticket shall be held on the call of the Chairperson."
At the Democratic Party gathering, the decision is made based on a majority vote by those who are present.
Republican Party regulations have a similar procedure too.