Search a disease called hexamita, commonly found in discus. Treatment is usualy a chemical called metro in the form of a food if you fish is still eating or a bath if you fish is not eating. Increase the temp in your tank to 86-88 and add aquarium salt 1 tablespoon per five gallons. Then add the metro as directed. Metro will not affect your tanks bacteria base, nor is it possible to overdose the medication. Hope your fish feels better !