When you say other corals, do you mean other SPS corals, or just in general? SPS can become very stressed with sudden changes that may have little to no effect to LPS or softies, a change is salinity is certainly a possible culprit. Its hard to tell from the pic, but are they just "sliming" or is their some loss of tissue??
If they were originally closer, that may have also caused this, if they arent losing tissue, get everything stabilized, make sure their is good water movement around them, and keep a close eye.