From my exp. a discus will just mysteriously "fall out" and wither away. Sometimes from social stress but many times for no apparent reason at all. Sometimes fish just don't fit in to a group for one reason or another. That being said I wouldn't rush to medicating your tank if the other fish are in good health.
Hate to say it but usually the best course w/ discus is to maintain optimal condtions and hope for the best and these things work themselves out. . . one way or another.
I think Hillbilly has a tank full of discus that didn't "fit in" in other groups. Remember discus are still cichlids. I'm not pointing the finger at pwn-age being your culprit, but it's something to be aware of. In small groups you end up with a "runt" at the bottom of the pecking order many times.
Hate to say it but usually the best course w/ discus is to maintain optimal condtions and hope for the best and these things work themselves out. . . one way or another.
I think Hillbilly has a tank full of discus that didn't "fit in" in other groups. Remember discus are still cichlids. I'm not pointing the finger at pwn-age being your culprit, but it's something to be aware of. In small groups you end up with a "runt" at the bottom of the pecking order many times.

They can make a decent display on their own, once they are no longer under stress, filling out and eating well.