Sick Goldfish

Hi there. I have a very sick goldfish on my hands and I'm not sure what I'm
doing to treat her is correct. A couple days ago I noticed she was kind of
just laying around her tank and then I noticed some white spots on the base
of her tail. I looked around online and found some information on Ich. I went
out and bought some QuICK Cure and put it in her tank right away. The next
day, she didn't look any better, her tail was starting to fray with brown
spots where the white ones were & white spots on her back. I drove into
PetSmart and told them my dilemma. They advised me to get a bigger tank (my
fish is 2 inches long), conditioning salt to add to her water, and some
medicine called LifeGuard, made by Jungle. They advised me to stop using
QuICK Cure, which I did, and start with this new medicine right away. I came
home, put in her medicine and added some salt to her water. That night, I
drove to PetCo to test my pH because I thought it was too low. Turned out,
the water was alright, but the guy I talked to advised me to get Stress Coat,
made by API, to add to her water to help repair her tail and skin damage. Now
today, she looks a lot worse, but some of the white spots have fell off and
the brown spots are completely gone. Her tail is still fraying and now she
has white spots all over her body and around her eyes, and now it looks sort
of like a white film? She isn't swimming around, just floating and breathing,
and won't eat because it's too hard for her to swim. If anyone could let me
know what I'm doing is correct or like to share some advice, I'd GLADLY
appreciate it soo much! I'm a wreck & I hate to see my fish be like this.
Thanks.