On Sunday, former Secretary of State Hillary Clinton collapsed while leaving a 9/11 memorial event in New York City. Clinton apparently began feeling ill during the event and decided to leave early. Though Clinton and her handlers had successfully kept the press pool away as they exited, a man not in the pool took video of Clinton waiting for her vehicle.

In the video, Hillary Clinton can be see first trying to support herself against a concrete pillar with a woman at her side holding her up, only to completely lose her balance and start to fall as secret service agents attempted to hold her up and get her to the vehicle.

Secret Service agents surrounded Clinton, making it unclear if she actually collapsed onto the pavement, but Clinton did reportedly lose a shoe. The vehicle then drove away where, instead of going to a hospital, it reportedly traveled to Chelsea Clinton’s apartment in New York.

Hours later, Clinton emerged from the apartment to wave at the cameras and do a seemingly staged photo op with a young girl before traveling back to her home in Chappaqua, New York. Clinton has now canceled further campaign events this week.

All of which raises the question: what illness is Hillary Clinton suffering from?

Clinton has been having coughing fits off and on for months and after a particularly nasty fit on stage during a Labor Day event, was questioned by the press. She said she felt fine and that the coughing was due to “seasonal allergies.”

But after the video of Clinton collapsing became public, the campaign had a new story. According to the campaign, Clinton had been diagnosed by her longtime personal physician, Dr. Lisa Bardack, with bacterial pneumonia the previous Friday. Bardack also went on to explain that Clinton had suffered overheating and dehydration at the event but now was feeling better.

Not surprisingly, the claims were met with well-deserved skepticism. The overheating claim was particularly problematic as the temperature at the time of the incident was a moderate 80 degrees Fahrenheit with low humidity. No one else at the event appears to have suffered any “overheating.”

Furthermore, Clinton’s coughing fits have been occurring for months, and pneumonia rarely lasts longer than a couple of weeks. If Clinton was diagnosed on Friday, why was she out in public shaking hands and hugging little girls for photo ops? Bacterial pneumonia is contagious.

She’s also 68 years-old, an age when pneumonia can be fatal. The last thing she should have been doing is campaigning.

It seems just as likely that Clinton has a more serious chronic health problem and is concealing it. What exactly it is can only be the subject of speculation, but the current story doesn’t add up and the Clinton campaign has blown whatever credibility it may have had on this subject by continually lying about her health.

The only thing that can be deduced is that if Clinton has a serious chronic health problem, it is one she fears disclosing to voters.