ADF With Lump on Back, Losing Weight Rapidly

[Gilltyascharged]

Hello! I have a 10gal tank with a cory catfish, a male crowntail, and two African dwarf frogs. They have all been in there together for about 8 months now, and seem to be relatively problem-free. However, my concern is currently targeted on one of my ADFs, Quasimodo. I got Quasi and his friend, Bandit, as a gift from my parents. They came from a woman on Craigslist who had a 5gal with frogs, but was no longer interested in them. When my dad arrived home, the first thing I noticed was that none of the decor had been removed from the tank, and most of the stuff in there was tipped over. There was originally four frogs, but one died that night, and the other, a large female, died a few days later. I believe both were stress/trauma related, as the female was extremely bloated and had cloudy eyes. The remaining two consisted of a rather skinny little guy (Bandit), and another with an odd lump on its back. The lump extended from the left shoulder to part of the lower back, but didn't seem to be causing any issues concerning movement. All of this occurred over a year ago, and many things have happened since then. About seven months ago I noticed both frogs developing cloudy eyes and rapid weight loss, followed by extreme bloat. I put them in a quarantine tank with antibiotics and everything cleared up, minus the clouded eyes. Those took a little over a month to resolve, but both remained healthy for another six months or so. Fast forward to the other day, and I noticed that Quasi was seemingly skin and bones. Bandit looks completely normal and is feeding fine, as well as One-Eyed Jack (my older bronze cory) and Obi (my betta). Not sure what's wrong, as the levels are fine and the filter and heater are working...I don't currently have any photos of Quasi, but will try to upload one if needed.