The first lady's spokesperson, which spoke to ABC News, declined to give a reason for her absence.
Melania Trump was last seen in public on May 10, when she joined her husband to welcome the return of three Americans who were being held captive in North Korea.
As recently as Friday, Grisham told CNN, "she is fine, she's doing great".
Drawing a parallel between her tweet and POTUS' earlier tweet, social media went on a rollercoaster ride cracking jokes and framing odd theories about the First Lady's tweet.
Among the more shocking unconfirmed rumors about Melania Trump's lengthy absence from public view and, apparently, from her official duties, comedian Tom Arnold has claimed to be in possession of a video recording showing Donald Trump physically assaulting his wife in an elevator, according to Movieweb.
Paolo Zampolli, a longtime pal of Melania's, told the Associated Press she "wanted to spend some quality time with her family". "Rest assured, I'm here at the @WhiteHouse w my family, feeling great, & working hard on behalf of children & the American People". She also joined her husband at their Florida estate to host the Japanese prime minister. "She's looking right at us right there".
US President Donald Trump embraces First Lady Melania Trump (R) during an event in honor of Military Mothers and Spouses in the East Room of the White House in Washington, DC, May 9, 2018, one of her last public appearances.