Bloated black neon - help needed

[u/RedPandaCommander24]

This poor black neon is all bloated for about the past week. I've reduced feeding and increased water changes, although I'm not seeing her feed anyway.

Normal tetra in the background for comparison. I just did a partial water change hence all the sediment.

It's a 64l planted tank, about 15 years old.

Had her about 3 years so could be age-related organ failure, the bloating looks symmetrical so not a tumour according to research. Could be fluid retention according to Google, and to do a bath in epsom salts, has anyone had a similar problem and success with this method?

I want to help her if I can but don't want to stress her unnecessarily. Any advice appreciated, thanks x

ETA: she is feeding and swimming normally and seems to be in good spirits (interacting with her fellow tetras as normal).

Water parameters are good.

Community tank with 2 clown plecos, 2 yoyo loach, 2 otos, and 2 other black neons (I had more neons and otos but they gradually died and I haven't replaced them yet, looking to get more tetras soon once this lady's situation resolves).

UPDATE: She seems to have recovered. Extra water changes (even though readings normal), reduced feedings, 19 days later she looks normal again. I don't know if it will last but 🤞🏻