Acro Problem

[CDick]

I got a purple&green acropora 2 weeks ago. The first couple of days it seemed fine until the purple started to wither.A day later the green did the same.The acropora also came with a crab.It hasn't bleached out or lost any tissue but the polyps haven't extended since i brought it home.I've also been feading live phytoplanton every other day.I don't have much experience in sps so i'm not sure so any input would be helpful.