Hey guys, So I have a powder blue dwarf gourami who's seen some . He was in a 20g with cherry barbs, a betta, a cory (lone survivor) and a platy. Well, I got ich on my platy and immediately dosed with nox-ich. I did the three day treatment as advised. The ich cleared up by the second day and by the third day half my tank was dead. The bottle advised no water changes until the fourth day and my tank heater took a nosedive so my tank was resting at ~78 or ~80. I cleaned out all my barbs, my cory, and my betta was moved already to a different tank for other reasons and I moved my platy to another tank. Well I thought the gourami would be okay to move so I could tear down the tank because it's been nothing but awful luck with disease, and when I went to move him I noticed he had a patch of red where a few scales were missing. Other than that no obvious ulcers or fin rot or mouth rot or anything. So I kept him alone in my 20g and the next day he was laying on the bottom practically sideways, He wasn't interested in food. I thought he would die for sure but it's now been two more days since everything else died and he's still going. Barely. I did a 25% water change today and the water parameters are near perfect. No detectable ammonia, nitrate or nitrite. But he was still laying at the bottom, leaning up against things or sitting tilted. But after the water change he's been floating toward the top but it's super obvious he can't stay up there without constantly putting in effort to do so. He keeps sinking to the bottom like there's rocks in his stomach. He is not interested in food. What could be wrong and what can I do to help him?