cats are weird sometimes. It might be that the shaving got her all anxious. If so, in my experience cats usually return to their 'normal' behaviours after a few days to a couple of weeks. It could also be the cold.
Barkingdog makes a good point about a potential sweater getting caught, but nobody knows their enclosure better than you. Just survey the risks or maybe supervise the cat directly to see if she feels any more comfortable with the sweater.