I think it's because you may have installed a plugin that is loading another copy of jQuery, an older version, even though the theme is already calling it once. So you have two versions of jQuery running, which is most probably causing the issue.
Could you disable any plugins you may have installed in the last couple of days and let us know if that helps?
P.S - Our plugin is designed to not load any scripts, like jQuery, if it's already been called once by either the theme or a preceding plugin. However, this is not always the case with other free/paid plugins.