sensitive 4 year old

[2kids4me]

Hi, I have a 4 year old girl and a 7 year old boy.  My son just started a new Elementary school and my daughter a new family day care because we have recently moved.  My son, who is very outgoing and friendly, has thrived in his new environment.  My daughter, on more of the shy and sensitive end, has not.  She has been having these crying fits at day care for no particular reason.  At first it seemed she was having withdrawls from being with her brother all summer, but now sometimes I think she is just putting on a show.  The day care provider says she changes emotions like the switch of a light.  She has been in daycare sense she was 1, she has never had a problem like this.  She knows that I come to pick her up everyday when I am done working.  I am very loving and caring with her.  I do trust the new day care provider that she is being very nice and caring towards her also.  She has excellent references, and has been in the business for 20+ years.  She has 8 children on her own and she is also understandably very upset by this.  I don't understand what could be making my daughter act up in this way.  She is terrified when the day care provider's husband comes home.  He has only said 'Hi' to my daughter one time. She has no reason to be afraid.  I know absolutely she has never been abused by anyone.  Is she going through a phase?  Is she just being overly sensitive?  Is she just trying to get attention?  If so, why?  There are 2 other girls in the day care who are slightly younger than my daughter who just love to play with her.  Why would she not be getting the attention she needs?  Is she insecure?  She is perfectly fine at home, and does not cry or get upset at all usually.  What is going on???  I'm actually debating pulling her out of the daycare because she seems so uncomfortable.  She has been there going on 6 weeks now.  It is not getting better with time at all.  Any suggestions?