Help, sick fish maybe?

[Llamarama]

just wondering...with all these water changes have you been making sure that the new water is the same SG as the water in the tank? what are you using to measure the SG? I would guess salt/ammonia burns as well maybe invest in a $30 kit that tests the main stuff...the API one is cheap...isn't the most accurate but gives a decent picture of whats happening...what kind of test was the LFS using? i've seen petsmart use stips to test and they don't give anywhere near accurate results