Help! Fish breathing heavy, loss of appetite

[George]

What do you use to measure salinity? There is a big difference between 1.009 and 1.010 in term of treating marine ich with hypo.
It's probably a good idea at this point to abort hypo treatment for now since it's not working for you. Raise your salinity to 1.017 slowly. The lower than NSW salinity is to help with metabolism of the fish and oxygen level.
After you get your fish look normal again, sans the marine ich, you can choose other methods to treat marine ich. Look up tank transfer method or copper to treat marine ich. You require additional tank(s) for those methods.
Good luck.