HELP! IDK WHAT TO DO ABOUT THIS! :(

[FISHQUEENIE]

MY GOLDFISH: here is what has happened.
JUly 31st - i noticed he had a small red bump on his head. i began treatment with ESHA 2000. but i skipped day 3 because i was not home... i regret this alot.
August 3rd - it seemed to get better, but a bit bigger with white spots.
August 4th - it got a bit bigger and stuch a bit out of his face.
August 5th - seemingly bigger, and with white thin film ontop.
August 10th - looked like it was about to go away, but still some red splotches.
Wednesday August 12th - it was bigger, restarted treatment with esha 2000, some skin pathces were falling off? unsure of what it is.
finished treatment on FRIDAY AUGUST 14th.
Saturday August 15th - it is bigger, but difficult to get picture. it is poppilg little bit otu of head slowly. white filamen ton top but no tmushroom looking.
TODAY AUGUST 17TH. MONDAY. - VERY MUCH BIGGER. it has cloudy white stuff and i thought it was healing but this doesnt look good! i dont ahve a hospital tank.

some things to note, he has had this bfore but it was smaller, then i added aquarium salt. i have not added aquarium salt yet. i have a 180L tank for four goldfish, yes ik its a bit small but he is the biggest one at 12CM. and im saving up for a 400L tank soon. I do weekly waterchanges but i should increase the amount rn. please help, any advice. ALSO yes his mouth has always been white, since the day i bought him. He likes to also scrape his head up against stuff eventhough i dont have very sharp decor. He is acting normally, swimming around, being with his fishy friends and eating with hsi appetite. he is completely normal except for this ulcer? idk what it is

PICTURES BELOW! PLEASE HELP!!! Im realy really really worried, and idk what to do im kinda new to fishkeeping but done alot of research, AI says its many different things and i try to find out but its so difficult!! help!

 

[Innesfan36]

I would do massive DAILY water changes. Upwards of 90%. The fish can take it with no issues providing the replacement water is treated and about the same temperature. How much have you been changing weekly?

Your tank isn't 'a bit small' but way too small for 4 goldfish. If I'm doing the math correctly you've got 4 goldfish in 31 gallons. Veteran goldfish keepers suggest 40 gallons for the first fish and 20 gallons for each one thereafter. And those numbers are minimums. Even then, near total weekly water changes, no less than 75%, are recommended.

 

[TNG3]

I totally agree with the advice above.
Regarding treatment for bacterial infections, you have eSHa2000 for a range of infections and eSHa Hexamita which is used for hole-in-the-head treatment. You need clean water for either treatment, noting that 2000 and Hexamita can't be used together so a major water change is needed to dilute 2000 if you want to try Hexamita.
How long has your tank been set up, recently or a few years?

 

[FISHQUEENIE]

I totally agree with the advice above.
Regarding treatment for bacterial infections, you have eSHa2000 for a range of infections and eSHa Hexamita which is used for hole-in-the-head treatment. You need clean water for either treatment, noting that 2000 and Hexamita can't be used together so a major water change is needed to dilute 2000 if you want to try Hexamita.
How long has your tank been set up, recently or a few years?

For over a whole year

 

[FISHQUEENIE]

I would do massive DAILY water changes. Upwards of 90%. The fish can take it with no issues providing the replacement water is treated and about the same temperature. How much have you been changing weekly?

Your tank isn't 'a bit small' but way too small for 4 goldfish. If I'm doing the math correctly you've got 4 goldfish in 31 gallons. Veteran goldfish keepers suggest 40 gallons for the first fish and 20 gallons for each one thereafter. And those numbers are minimums. Even then, near total weekly water changes, no less than 75%, are recommended.

okay! thank you so much! you see, i was only getting two goldfish but then my dad bought two new ones and was trying to put them into an unfinished pond! i had no choice but to help them, so thats why the tank is small for the four goldfish... i will be doing the waterchange immediately thank you so much