I lost a Discus

[Diamond Discus]

I lost the female to my Orange Scorpion pair. I don't really know what I was up against. It had to be bacterial. She started out listing a bit and I noticed her eyes were swollen, so I took her away from her mate and put her through a 10 day round of EM and 1 T. salts per 10 gallons. She seemed better but her eyes were still swollen, she had been eating but not with the vigor she normally would have. I put her back in with her mate and she started to get worse over the next 5 days, fins started rotting away and she quit eating. Her eyes started to get even more swollen than before. So I pulled her again and started with a gram negative antibiotic (tetracycline) and today which was day 3 of the treatment she died. I had made 90% water changes with aged, aerated, and heated water every day for the last 20 days. She felt super slimey but her gills looked good. her eyes were so fluid filled. Anyone know what this was?? Her mate is fine so far. :confused: I have luckly used dedicated equipment and I'm bleaching everything she came in contact with right now?

I'm just so sad to lose her.