URGENT! Bacterial + fungal treatment options

Mar 11, 2018
Meet Barrance, I have had him for 2 years and he has always been super healthy, active and exploding with personality. He has never been ill before.
I noticed this spot on his back behind his top fin and tail fin. After tons of research, I was convinced it was colomnaris...I just started treating him yesterday with aquarium salt and furan 2... Today he had his 2 nd dose of furan. He is not lethargic and still has a healthy appetite today.
Today I found stuff about fungal diseases that mad me think it might be fungal and not bacterial!!! Can someone help identify his disease and help me treat it? Could I treat him with ampicillin while using furan? I just really love my fish and don't want him to die...I will do whatever I can. I ordered kanoplex today as well...
To answer questions, he has a heater and filter. And is in a 2.5 gallon container. I just took out all of his gravel and plants.