Although it is difficult to diagnose from long distance, I would guess a systemic bacterial infection brought about by a combination of disease in the feeders and possibly poor water quality brought on by leftover "bits". Treatment with a full-spectrum antibiotic regimen would seem to be indicated. You might try Maracyn and Maracyn Two together, remembering to remove carbon and any large organic deposites from your filtration and do large scale (say 50%) water changes between doses. The antibiotics will affect your biological filtration as well as the bacterial affecting your fish, so you might want to move the biologically active media to another tank for the duration of the treatment (or set it up on a Rubbermaid tub filled with tank water to keep it active).