Sometimes reactions to certain things can be just as slow as they are fast. It took 6wks for my 5yr old Favia to start bleaching from to much light. Moved it and 2wks later she was back to normal.
I also know that ALK swings are very hard on Acros. Weakening them, thus making them susceptible to disease. Couple that with media change and I would expect some loss.

Personally I wouldn't try anything else. Let things settle down. Maintain parameters, keep them stable at whatever numbers you choose.