It's most likely not the salt that is bothering her, rather some pain, & rays don't like big changes. Salt actually has a soothing effect as it stimulates slime coat regeneration. Moving a healthy ray to a different tank alone can cause rays to sulk for days. She is not feeling well. Give her some time. Try feeding her favorite foods, but if she doesn't eat, then remove the uneaten food, wait and try again the next day.
Rays are largely nocturnal, so the fact that she is digging in sand is a positive sign. In their natural environment they do it looking for snails & other food. The fact that she is active at night is also a good sign.
Skin regeneration in an aquatic environment is slower than for land animals, so be patient, the healing process will take some time. I had a new adult male black diamond ray that only ate 2 tiny pieces of shrimp in 5 weeks. They can be super stubborn, & though it's not ideal, she wont starve to death