Possible Health issue

My tank set up is about 2-3 weeks old. 37 gallon tank. Fish have been in it for about 2 weeks now. I just did 60% water change after adding 7 new fish. 1 new fish and 1 old fish have stiff hanging from them. (As I'm Writing this I happen to look up and the older fish just lost its thing). The new guppy wont come out of the barrel much and when it does it goes back in. I dont think its eating. What's going on with them

All I see is poop hanging. Did you cycle your tank before adding fish? What are your ammonia, nitrite, and nitrate readings? Are you aware of the aquarium nitrogen cycle? If not, please read. https://www.fishforums.net/threads/cycling-your-new-fresh-water-tank-read-this-first.421488/