Jewel cichlid with protruding gill

Hello, I've searched far and wide but haven't been able to find a solution.

My jewel cichlid has had a red swollen/protruding gil for several weeks now and getting worse. Just one gill is affected. No gasping at the top and she eats fine. Pictures attached.

Could anyone offer any diagnosis?
Any help is appreciated!!

Little background:
She is several years old, and I noticed this issue several weeks ago (late January). I put her in a 10g hospital tank a couple days after that and the treatments have definitely made the parameters suboptimal at times. I change the water every other day but antibacterials kill all the good bacteria... I test everyday and keep the amonia "safe" but hasn't been 0.
I've tried treatment with: salt, melafix, api fin and body cure, api general cure, furan 2, erythromycin, words of love and encouragement

Hi and welcome to the forum

Can you post a couple more pictures of the fish? One from each side for comparison and one or two from the back half looking forward so we can see behind the gill cover, and maybe one from above so we can see how much it sticks out.
Try to clean the glass before taking pictures so we can tell what is on the fish and what is on the glass or in the water

If there are ammonia, readings, do a 75-80% water change every day until the levels remain on 0ppm. Any ammonia can kill fish and will harm fish that already have health issues like a gill problem.
Make sure any new water is free of chlorine/ chloramine before it's added to the tank.

Colin_T said:

Hi and welcome to the forum

Can you post a couple more pictures of the fish? One from each side for comparison and one or two from the back half looking forward so we can see behind the gill cover, and maybe one from above so we can see how much it sticks out.
Try to clean the glass before taking pictures so we can tell what is on the fish and what is on the glass or in the water

If there are ammonia, readings, do a 75-80% water change every day until the levels remain on 0ppm. Any ammonia can kill fish and will harm fish that already have health issues like a gill problem.
Make sure any new water is free of chlorine/ chloramine before it's added to the tank.

Click to expand...

Thank you so much for your response!
Ammonia is back at zero, but wanted to mention there have been spikes from the treatments I've tried/lack of a good biological filter in the hospital tank.
The pictures from rear are really hard to get! My best attempts are attached. Her other side is completely normal, but the bad gill is very glad. Luckily she is swimming around and seems to be ok behaviorally.
Please let me know if you have any ideas, and thanks again!

Is there something pink growing out from behind the gill cover?
If yes, then it's probably a gill tumour. These occur sometimes on fish and there is no cure. You leave the fish until it has trouble moving, breathing or eating, and then euthanise the fish. They aren't contagious and are just a growth that sometimes occurs in fish.

Yes it is a pink growth.
Wow I didn't expect that, I'll return her to home and live out her years.
Thank you again for your time and advice, I really appreciate it!