I had this same issue and after a bit of searching, this is what i've added to my .htaccess file.
<FilesMatch "\.(css|js|php)$">
FileETag None
Header unset ETag
Header set Cache-Control "max-age=0, no-cache, no-store, must-revalidate"
Header set Pragma "no-cache"
Header set Expires "Wed, 11 Jan...