Hello Betta world.
Ok so i've had my betta for i'd say a month now, and in the beginning he was fine- bubble nests and all that good stuff. But recently i went to mexico and my family didn't clean his tank, so he basically was sitting in the filthiest water imaginable. I quickly cleaned it and added Nutrafin to condition it.
He truly needed a bigger tank so i bought a 5g and now he has stopped eating and swimming. All he does is lay on the bottom of the tank under this elephant toy thingy all day & night. He only comes up for air and then straight back down. Im so worried. I know he's stressed, and has a some fin rot so I added Seachem Prime and im just starting Betta Revive. But my main concern is the fact that he has a white barnacle looking thing right above his mouth. From what i see with the magnifying glass (drastic measures I know) it isn't stringy looking like columnaris. And he is white where his bladder is, but it doesnt look bloated. Every time he swims up for air I try to sneakily place food on the top, but he stares at it and swims down.
I guess i just want to know what to do. Im new to this all and I didnt imagine i'd be spending $50 dollars at petco on a fish. My mother is the type of woman who says "Oh he doesnt need a big 5 gallon tank" she doesnt like to spend money.

And i dont have money.. im 15.. yeah.
My camera's out of charge but once i find my charger ill add pictures on what he looks like.