Please help with sick dwarf gourami
 

I have a cobalt blue dwarf gourami that I've had for a couple of months or so. He's was doing great, eating well, following me when I'd be near the tank, just doing really good. Lately, though, I had noticed he wasn't swimming much, just kinda suspending near the bottom or sometimes the top, not coming to the top to eat when I feed, just acting very lethargic. Then today, I noticed a large knot on his left side about midways between his tail and pectoral fins and he looks kinda crooked and seem to struggle to swim. I have no clue what's going on, all my other fish seem just fine, I can't tell if it's an injury or if he's sick and I don't know what to do for him. Any and all help greatly appreciated.

Is there any chance you can post a pic?

Yeah, I'll try to.
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I can't get a clear picture of him. Every time I try, it's so blurry that you can't make it out. He's getting much worse, the knot on his side is bigger, there's a clump of white matter on one of his feelers (the long appendages next to his pectoral fins, the proper term has left me), and he's seeming to struggle staying upright. I'm afraid he'll be dead very soon, but I don't know what to do for him. I'm also concerned for my other fish, but they still seem ok. I would quauantine him, but I don't have another tank. If anyone has any ideas, please help.