29 gallons is too small a tank for discus. That's for starters and as mentioned earlier they do better in groups, however, only if you upgrade the tank. Rule of thumb is 1 fish per 50 litres. Don't introduce new fish if your one is sick. Forget the salt unless the fish is suffering from whitespot or Costia. Increase temperature to 34 degrees and add an airstone, don't feed any bloodworm. You drag in more diseases than you can shake a stick at and it has a very low nutritional value. Check your water for ammonia, nitrite and nitrate