Can Someone Please Help to Address the Situation of My Tank?

Even the best fish stores can accidentally sell a sick animal sometimes. Any idea how long these animals had been in? If they hadn't been in long, symptoms might have not manifested yet.I would try raising the temperature as high as all of the animals can take, slightly faster than you would normally. While the situation is drastic, the various microorganisms causing the disease will not adapt nearly as well as the fish. Avoid thermal shock, but do it as quickly as you are comfortable with. If you have a HOB filter, I'd get a 12 pack of micron-rated pads, and replace them every three days until you're out. Keep up the water changes. Don't give up!