One Discus laying flat after water change

[discus6628]

I did water change yesterday. All other fishes are ok. Except one fish after water change is standing still in one spot and not moving. Today, when I got home, he is laying down flat. Not sure he hurt himself or not. During a water change yesterday, I hear a splash. May be he jump hit the tank or drift wood. Today I found one white spot from his body. The fin is fine and not clapping. Currently I moved him to separate tank by himself. Please advise should I do anything? Salt, medicine or pray? Please help

8310083099

[Allwin]

Is he breathing? the best is just leave him alone and hope for the best imo.

[discus6628]

he is breathing fine. Just laying flat. I already separate him in his own tank. Guess I just hope for the best. Ouch. My 7" big discus......