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Donald Trump speaks at a rally in Florida.
The Republican presidential candidate wished his Democratic rival a speedy recovery, but asserted on "Fox and Friends" that "we have to figure out what's going on."
"I don't know what's going on. Like you, I see what I see," Trump told the Fox News panel. "The coughing fit was a week ago, so I assume that was pneumonia also. I would think it would've been. So, something's going on, but I hope she gets well and gets back on the trail. And we'll be seeing her at the debate."
The real-estate magnate also announced during Monday's interview that he will be releasing "very, very specific" results from a recent physical later this week.
Though unscientific speculation about Clinton's health has been a fixation of fringe right-wing media outlets for months, some political experts believe it is in the former secretary of state's best interest to release a more detailed medical history following her unexpected exit from a 9/11 memorial service due to her pneumonia.
"Her current level of health transparency is not sustainable. She will need to release medical records before the first debate," top Republican strategist and President of Potomac Strategy Group Matt Mackowiak told Business Insider in an email.
In August 2015, Clinton became the first major 2016 presidential candidate to disclose some of her health records. She released a note from her doctor detailing her recent medical history, including her hypothyroidism and recovery from a 2012 concussion.
Trump has largely ignored calls for greater medical transparency, only publicly releasing a brief note from his gastroenternologist proclaiming he "will be the healthiest individual ever elected to the presidency."