Have you tested all your tank parameters to see if anything is out of place? Its pretty much impossible to save/make fast changes that saves corals. The thing with SPS corals is that if the water parameters are the cause of RTN/STN/Bleaching, then correction of those parameters must be done in a controlled fashion...which means there are no quick fixes. Moderate daily water changes do really help and is just about the only thing you can do to help your corals.
Suspending Carbon dosing/heavy GAC and GFO use if these are being used does help too.
Test all your water parameters of you havent done so. Sometimes SPS just die because they want to make us feel gutted. But generally, water parameters or use of GFO/GAC/Carbon dosing etc are the culprits.