I have a piece of skin that has separated under my foot. it's seems to have grow detached like something is in it. ?

Tag, your it.: Anything growing, partially attached, from the bottom of the foot needs to be examined. A specialist should be able to quickly determine the proper treatment plan. My concern is if this piece continues to grow and/or gets ripped loose, an infection could be started and things could get a whole lot worse. It is best to have it examined and remove all doubt.

Maybe you are : Right. Go see a doc too find out if there is a foreign body or not.

Seek examintion: I agree with the other responses already posted. It is important to have the skin examined by your healthcare provider to try to ascertain exactly what is going on.