I’ve had my betta for about 2 months, and he was very healthy for the first 1.5 months, but about a week ago, he became very lethargic and staying up in the very top corner of his tank, not eating and with clamped fins. The water parameters were 0 chlorine, 0 nitrite, traces of ammonia, and traces of nitrates. It only lasted one or two days before he was back to normal. Now, he is very lethargic again, I would say worse than last time, and he is still not eating, and instead of being in the corner of his tank, he either squeezes between the filter and the glass or lays on the bottom in a plant. His breathing seems labored. I tried to do a 25% water change (I treated the water and ensured it was the same temperature before I added it) but he is still resting on the bottom breathing heavy. I know his gills are black, I got him that way, so that is not new. I have now seen and heard him making a clicking noise twice now, he lifts his head up and a click comes out. He does it 4/5 times then no more. When he does swim, it seems almost as if he is shivering and it is very twitchy and abrupt, he often will end up hitting the side of his tank. It is very sad to see. Please help, I don’t know what to do!