If your brain coral is Trachyphillia, I can't say anything - they are dying for me, no matter what (bought damaged, though). But symphillia, cynarina, scolymia, lobophillia and maze recovered just fine, in 2-3 months, in the gentle surroundings: low flow, away from heater, not a brightest place in the tank, until recovers or shows progress, and no mechanical damage during cleaning or after contact with the sand.
I'm using refugium in the sump for this with diffuse daylight plus low-moderate PC light. When starts recover, more might, gradually.
Once had set a shallow 4g Rubbermaid container as a separate hospital tank, with old water and LR from the main tank, it worked fine too.

The bags are with carbon and Purigen.
Only once I had seen LPS (candycane, actually) losing tissue - there was a very high pH 8.8 with other parametes within norm.
If nothing helps, you may try some kind of anti-bacterial treatment in a separate container. I tried only Melafix with Primafix (for other corals, but the symphyllia, bought in a bad shape, was present in this tank too), it started to recover, eating at last.
I'll keep fingers crossed for your coral.