Single Button polyp not doing Well on Colony?

So, I have a frag of buttons with 15 good sized polyps on it and the largest one in the middle of the colony has not been doing good for the past week. It's all droopy, wrinkly looking with a gaping mouth. It always stays half closed. I don't know why this one polyp is doing so bad because the rest of the colony are perfectly fine, except for the polyp beside that one which has turned itself inside out and has been like that for about a week. There are new polyps popping up, so they are spreading nicely. Why is there only 2 polyps doing bad but the rest are fine? I also have star polyps, green stripe mushrooms and zoanthids. My buttons all use to be fine, it's just this past week 2 of the polyps in the colony are doing bad. My parameters are all perfect!! and my other corals are great.

 

oh it's a 33 gallon tank 2 39watt t5 bulbs, one white and one blue. in a lower flow area on a live rock hear the middle of the tank.