Btw, it is still moving around and eating. I just removed it from a piece of liverock it was on and it's remaining arms were attached firmly with their suckers all out.

I read your other post. You stated "but I didn't research about acclimating prior to putting it in my tank", and I only saw one person say that they just throw them in their tank provided salinity was the same but also said it was bad advice to do so. There is not much you can do at this point accept keep feeding it as you say it is still eating. You could try soaking the food in Selcon, it helps with fish but I'm not sure about the benefits with a starfish. If it looks like it is getting worse you should remove it. Nobody like to get rid of something still alive in the tank but if it is deteriating then for the sake of the other inhabitants it should be done before it is too late.