This is the problem, stress kills, so moving again can in itself be a killer. As others have suggested, dose prime, and get incremental water changes ready. This will remedy the ammonia issue, and if that is the problem, he should rebound fairly quickly.
A couple of questions? Did you check the sg in the bag before introducing him to the tank, what is the sg in the tank? Most lfs and suppliers at the best run 1.020, many even lower, so if you put him in reef conditions at 1.025/26 that is a very big problem.
2nd, does it look like he is having a seizure and does he lose color color when he flashes.
Less deadly common issues like flukes or parasites will give you time to assess and react appropriately. 1st the ammonia issue needs to be addressed.