The only thing i can think going wrong in here is you are doing a lot of experiment on that fish to keep her good which is harming her. I dont give my new fish so much medications and water changes as they are already stressed out by travelling from breeder to retailer and from retailer to our home. Just give them enough time to settle down and be relaxed. And please do the filter changes as joe has told you and let that fish take care of itself. One more thing i do when i buy a new goldfish is that i buy a pair as i think they are social animals and they love to have company of their own.