Just pretend it isn't there and continue on your normal routine.
Don't spray reef roids at it. It isn't needed and will only irritate it further.
Sometimes the best action is to do nothing. Sometimes people panic and make things worse constantly moving things or trying to tweek lights/flow/water all at once. Your coral needs time to adjust.
All mine grew from a single head and I just ignore them and that is how they like it. I feed fish, dose to maintain alk/ca, and do water changes every 1-2 weeks and nothing else.
The large colony to the right was the one that looked completely dead (had 3 heads at the time).
MVIMG_20190620_211900 by
Tana Jahangier, on Flickr