So this may sound weird, however I currently have mod_rewrite set-up to pass 2 variables through.
RewriteRule ^profiel/(.*)$ index.php?p=profiel&user=$1
In the second var (&user=), it passes a username which is retrieved through GET in PHP. However, some of the usernames can have question marks in them. However if this is the case, the question mark won't be passed to the GET variable. (For example: "www.example.com/profiel/whoami?" ends up as just "whoami" instead of "whoami?")
I honestly don't know how to solve this problem. Any help would be great!