If she's shedding in pieces, then you haven't really fixed the humidity. You changed the substrate which might have increased the humidity, but not to the appropriate level necessary for her to shed all in one piece. I would take the recommendation for covering the top of the cage with foil or plastic. Also, did you answer how the cage was being heated and how the heater was being regulated? That's important.
First things first is to get her thru this shed - fix the top of the cage so it will hold the humidity, and then mist the cage down.