Sunken belly, normal behaviour. Is it tuberculosis?

[Jotadese]

Hello, I need you to please help me identify what may be attacking my aquarium. 7 weeks ago I moved into a new apartement. The water pH is 7 now but before it was 6.4.
After that, everything was a mess, almost 4 weeks, the fish were all cornered, not trying to eat and stressed. As the days passed, they began to adapt and were swimming freely and normally, ate dry food, porridge, brine shrimp, etc. One day I began to see that 3 discus were dark and moving away from the group, which made me realize that something was happening. because of those sympthoms I decided to medicate the aquarium against a possible bacteria attack and apparently everything got better. One week later, 2 fish stopped eating but did not hide, did not have white feces, nor did they show signs of stress or abnormal behavior, they only stopped eating. The funny thing is that when I approached the aquarium, they also approached the glass.
They spent the days without eating, which caused their stomach to appear sunken, they began to lose weight, but they continued swimming through the aquarium, although slowly, the gills looked dilated and wrinkled.
These two fish died after being medicated in a hospital aquarium with metronidazole and prazincuatel.
Today I have seen a new discus with similar symptoms and the truth is that I no longer know what it can be, the fish swims at the top and slightly inclined towards the ground.
Please, if someone has had a similar experience, can you help me identify what may be the cause, maybe something in the guts, maybe tuberculosis?

[Iminit]

How is the water in tank and out of tap? How often are you water changing and how much? What’s the temp in the tank?

[Jotadese]

WC twice a week, 50%. 30 Celsius. ph 7. the tank have been treated with metro 2 weeks ago and wormer plus last saturday. if ypu look close to the gills, they are like dilated.

[Iminit]

The gills do seem inflamed. Could there be something in the tap water that bothering them? Ammonia chloramine? Do you use prime? Is 30c the normal temp you’ve kept them at?

[Jotadese]

The gills do seem inflamed. Could there be something in the tap water that bothering them? Ammonia chloramine? Do you use prime? Is 30c the normal temp you’ve kept them at?

actually, the gills are like overgrown, but they are not red but withinsh. i do use twice dosis of prime in each wc. 30C is the daily temperature since i move in because of the whole story i have wrote at the beginning of this post. What doesnt make sense to me is the behaviour of the fish, it was eating normally, then he gradually stops doing it. now does not eat anymore but still swimming at the top of the aquarium, not feces at all, sometimes headstanding.

[Rob Lewis]

If you search this site for flubendazole you may get your answer.

[Jotadese]

I found it finally dead.

This was the process.

Apparently normal in its behavior, it does not hide, it does not fold its fins.
Normal swimming, except when kept static, can lean towards the ground slightly.
Enlarged or inflamed milky-colored gills.
Gradually stop eating and lose weight.
Stomach looks sunken.
It begins to lose color.
Swims erratically and tilted looking at the ground, always on the surface.

if someone could agree something or experienced a similar situation, would be great.