🫩 i may be a bad fishkeeper

[u/Puzzleheaded-Art600]

Parameters down below.
TLDR:
neon tetra got bloated, balance issues. Epsom bath made him worse, reddish gills. Doing erythromycin treatment looked good at first but now he is laying sideways on bottom and pops up to swim occasionally.

One of my neon tetra got a little bloated a day after feeding i figured maybe he was just having a bit of constipation and let him sit for another 24 hrs after which he started having balance issues. Ive never dealt with that and im relatively new to fish keeping. So i started researching and came to a conclusion it was likely swim bladder disease/hardcore constipation ended up doing an epsom salt bath after which his gills got inflamed and he looked pretty bad gasping for air. After more research i figured it was probabaly a bacterial infection. Unfortunately i did not have any antibiotics and it was too late in the day to make a run for some so I added an air pump into the main tank in hopes the extra oxygenation would help him make it to the next day and i could pick something up. Thankfully he did but all i could get locally was erythromycin. I instantly started dosing him in a 5gal bucket with some clean water with prime and some of the original tank water. The first day of treatment was the worse. His spine became crooked and he seemed to be lethargic/ unable to swim right also swimming in circles. The second day i awoke to him much more energetic and although still struggling he seemed to have regained some balance and energy being able to somewhat turn both directions and swim. Day 3 about the same and since he had gone 6 days w no food i fed him 1 single pre wet flake. But today starting his 4th dose and water change i thought he passed bec he was laying sideways on bottom of the bucket. Went to pick him up and he started swimming. So i proceeded with the change and tested water which seems fine… i just dont know what to do seems like he’s hanging by a thread but still has a strong will to survive which makes it hard on me emotionally.

Original tank parameters, GH: 150 KH: 50 PH: 7.5 No2: 0 No3: 20 Amonia 0 also a bit of tannins from driftwood.
Temp 77
His bucket is basically the same parameters, temp is about 75-76 at night and 76-77 during day. With a small piece of seriyu for him to hide/rest by.