The find command has a ctime option that you can use.
To locate all files modified the last 5 minutes:
find / -cmin -5
If you have other filesystems mounted, then you might want to use the -mount option so that places like /mnt/cdrom aren't searched. On some systems this opton is called -xdev instead.
find / -mount -cmin -5
Also, you might want to do this as root, because several directories can't be searched by a regular user, and this will result in a large number of error messages if you don't redirect stderr to /dev/null. ( 2>/dev/null )