I came back from the weekend, and my betta's face appears split down the middle in color. One side is slightly lighter than usual, but the other is very dark in an area, and he is not using his lateral fin on that side. He doesn't want to eat, and keeps hiding. He is usually in a 10 gallon freshwater tank with 2 female guppies and a molly. they are fine so far. I have moved him to his old betta tank with clean spring water (slightly warmed). Help? I don't know what it is. I put a piece of the antifungal pellet in his smaller tank, and one drop of Quick cure. It appears a little swollen around the gill that has the darker area.