It sounds to me that your discus have become stressed, and the ever oppurtunistic intestinal protozoans ahve taken control. Follow the metro protocal you will find here. But even more importantly, find the stressor.
You have a community tank. What aggressive fish might you have? Gravel? UG filtration? Water chemistry and parameters? Where is your tank located? High traffic area? Kids tapping on glass,? Etc, etc., etc..
Mat