Bummer about the female. Do or did your Discus have stringy faeces if so this is worms or Hex as Blue&Kim said or Hole in Head, hard to tell unless you have microscope. If so worm with dog wormier or if your vets nice he might get some Metronzindola (sp). If you think fish are ok and eating and on sign of stringy pooh just mix in with food some how. Get some white worms for them they will love u for it. If you can't get any up your way I will send you a starter culture.