Betta was treated for fin rot few weeks ago. Everything resolved and fins looked better. About 4 days ago now I noticed he was laying on bottom of tank. I moved him into quarantine tank with less water so he could get to top easier. He’s currently eating small amounts. He’s laying on the Betta leaf’s I have set up for him. As soon as he comes off of them he sinks, then begins to swim erratically around then comes back on the leafs. He’s not bloated, not curved. He’s a white Betta and some areas of him are darkening. I put aquarium salt in tank to see if that helped. Fins look better but now the swimming is an issue.