Welcome to SD Inkidu! I'm sorry for your troubles with your discus. Your post would probably get the right attention in the Disease Section of the forum. Maybe a moderator will move it, but in the mean time, you are aware of your equipment and water parameters, but it will be helpful to tell folks on the forum to help you better. Please copy/paste this questionnaire with your answers as soon as you can.
http://forum.simplydiscus.com/showthread.php?t=38545