He was pushed down on a hard foul by Harrington in the Knicks game. Looked like he fell on a cameraman and he left the game holding his back. Just another injury...
Remember Celtics dont need KG till playoffs. Right now they still got Allen Pierce and Rondo so they will be fine if KG even is really injured that badly.
Reports come in from the locker room that KG had the offending camera brought into the back so he could point, yell and pound his chest at it.