A pic would help to see how bad the damage is. Adding some stress coat is fine. Do some extra water changes to keep the water pristine & nitrates as low as possible (under 10ppm, preferably under 5ppm). Unfortunately, there really is not much else you can do right now other than keeping the water healthy and observing the fish closely. I would suggest increasing the salinity to .05% but its not compatible with loaches so skip this. You will need an eye out for signs of infection and fungus (red blotches/streaking, white fuzz/film, white hairs/strings, degradation of tissue, etc). Keep us posted!