’ve experienced something like this before. Two millies I had swelled up around the base. The bubbly areas were hard, not pockets, like others experienced. It seemed to be the skeleton itself, not the flesh. IMO growth was effected. I really think flow was the culprit in my case, though I’m not certain. I read how flyguy said he was bumping up his mag around the time of his occurrence. During the time I noticed bubbly skin, I was also raising my mag. It is really hard to pin point the cause. I found that corals did not return back to normal but maybe that’s just me. Good luck.