You could try a metro dip. Metronidazole as most reefers have that on hand. 5min dip in full SG (1.026). It's hit or miss.
If that doesn't work, you could try a iodine dip. Lugols solution the same way. Once again, hit or miss.
Isolating infected corals from other corals is advisable. I understand that's not always possible.
Best of luck to you.