Has she learned this behavior from anywher saying shut up, does someone lese in the family or a babysitter say it to her, very often behavior like this is learned, so check out what others are saying and doing ,the ones she is around regularly.She sounds upset, does the day care stimulate the children in their care, do they get some outdoors time, reading, games , sometimes boredom can be a factor in Bad behavior , look beyond the box to find out ....