In this March 30, 2016, file photo, Republican presidential candidate Donald Trump speaks at a campaign stop in Appleton, Wis. (AP Photo/Nam Y. Huh, File)

Gosh, Donald Trump must "lack the mental and physical stamina to take on ISIS" or the presidency or even the campaign trail.

The Donald's staff, it seems, has canceled three major speeches and rallies that were scheduled in Colorado, Nevada and Oregon — including the one billed as his important immigration reset and reset of the reset.

Perhaps he had to go home and take a nap. Apparently he's tired himself out by excessive worry about Hillary Clinton's health. Perhaps he has a headache caused by his constant lies and the Pinocchio nose-out-of-joint syndrome that must create.

More likely, he's cancelling because he and his legions are realizing the waste of time and money in campaigning where he can't win, but logic has rarely gotten in the way of Trumpiness, so perhaps he and his top surrogates just needed a little more time to gin up ways to sow doubt where there should be none about Clinton's health — or emails, for that matter.

Just as "birthers" — Trump chief among them — used similar outlandish innuendo to question Barack Obama's U.S. citizenship, the "healthers" are trotting out conspiracy theories that Clinton is suffering from a brain illness.

Depending on the maliciousness of the moment, they've floated speculations of brain injury, stroke, Parkinson's, autism, early-onset dementia, even syphilis.

The take-off point was Clinton's fall in 2012 when she suffered a concussion just days before she was first scheduled to testify before Congress about the Benghazi terror attack.

Bill Clinton has summed up the rumor-mongering attack on Hillary well: "First they said she faked her concussion, and now they say she's auditioning for a part on "The Walking Dead," he said recently to laughter.

In 2014, after Hillary left the State Department and it was looking increasingly as though she would become a formidable Democratic candidate, Karl Rove started the newest fantasies suggesting she had brain damage after that fall and an ensuing blood clot.

"Thirty days in the hospital?" Rove ruminated. "And when she reappears she's wearing glasses that are only for people who have traumatic brain injury?" he said, according to a New York Post report.

The whole treatise was a lie. She was hospitalized three days, not 30. Prismatic glasses have a number of uses.

Then came Clinton's moment of fun-housing with reporters who were peppering her with questions at a muffin shop in Washington, D.C., a few days before the District of Columbia's Democratic primary. Clinton grinned at the reporters and bobbed her head in an exaggerated way.

Someone's video of that moment was then set to slow-motion loops and eventually headlined with the word "seizure."

But The Associated Press reporter showing surprise, who was also caught on the video, has debunked the poor attempt at propaganda.

"I've never been part of a conspiracy theory. Now, video of my surprised facial expression has become Exhibit A in the latest unfounded speculation about Hillary Clinton," wrote Lisa Lerer in a column about the incident.

Lerer recounted the questions about Clinton's meeting with Elizabeth Warren and what she saw as playful evasiveness, not seizures. "After the exchange," Lerer wrote, "she took a few more photos, exited the shop and greeted supporters waiting outside."

There also have been faked medical record "leaks," debunked by the doctor whose letterhead was attached, and a blurry photo purported to be a Secret Service agent's hand holding an auto-injector for an anti-seizure drug. The Secret Service says the agent was holding a flashlight.

Meanwhile the so-called physician statement of health that Donald Trump released a few months ago is dated Dec. 4, 2015, and sounds like parts could have been dictated by Trump himself: his blood pressure and lab results "were astonishingly excellent" and "If elected, Mr. Trump, I can state unequivocally, will be the healthiest individual ever elected to the presidency."

There also seems to be a question about whether the doctor who supposedly wrote the letter for Trump is actually what he says he is — a fellow of the American College of Gastroenterology. The ACG told MSNBC's Rachel Maddow that he was no longer a fellow and hadn't been since 1995.

Whew. Words fail us.

There simply is no appropriate name for the sickness that is this year's Donald Trump presidential campaign.