If you have a magnifying glass, before diagnosing and treating zoa pox, try to put polyps in a shallow container, fully covered with tank water. Wear safety glasses/goggles, just in case any squirt action occurs. Make sure the "pox" are not just large sand particles taken into the polyps tissue, as Palythoa will take sometimes large pieces of substrate in that can be confused with pox.
Pic quality makes it difficult to know for sure, without the magnifying glass- but looks like pox to me. Does not look too late to treat. I don't recommend treating unaffected polyps till necessary.