So here is what happened. I had gone on a week long trip and had done a larger than normal water change around 75% when i got back. The water parameters are now 0 ammonia, 0 nitrites, and 0.5 nitrates. After the water change he was acting normally even ate the 2 pellets I gave him. Then he bumps into the floating thermometer in his tank, it's a Marina Floating Thermometer. Now he is not swimming properly, he mostly floats without moving or stays on the bottom of his tank not moving his fins. He also stays in a curved position but he is able to straighten when he swims a little. At first he would also sporadically burst into rapid swimming so fast you could hear the water moving in the tank. He doesn't do that anymore, but now I have been keeping his light off and have a towel over his tank to block out light since whenever there is any light he hides behind the filter. He ate 2 pellets this morning but still floats not moving, occasionally he moves his fins to stay in the spot he is at. He still stays in the curved position when he floats. My sister thinks he is just stunned and that he will be fine after a few days but I'm still worried since it has been over 12 hours since this first happens and still no change. I tried to take a picture of him to post but he hides when I try. He is in a tank that I had done a fish less cycle on for over 3 months, 2.6 gallons Marina 360 Tank. There are some java moss and duckweed in the tank and a moss ball. The conditioner I use is Seachem Prime. His filter is fitted with a cross stitch mesh plastic to keep him from going under the filter since the tanks review say that fish can get stuck if they get under the filter, and I fitted a sponge onto it to slow down the water flow. He is a dumbo half moon, I have had him since January. Pictures of him when he first came home Jan 17, 2017 and today April 12th, 2017 are included below.