Separation anxiety

So, as you all know, my daughter started a new school a couple of weeks ago.  She did really great the first week, but then, on her second week, she started screaming/crying, she was so upset.  She didn’t want to go to school.  If she had to go to school, she wanted me to stay.

Then, when I wanted to go to Mom’s Night Out and I went to give her a hug and kiss good-bye, she started crying, “No Mommy, don’t leave us.”  Then, she did the same thing when I tried to leave to go to a doctor’s appointment.  It’s so sad to hear and see her crying because she doesn’t want me to leave.

Also, when I come to pick her up from school, the teachers say she has been fine all day up until right before it is time to leave.  Then, she asks if Mommy is coming to get her now, and she starts to cry again.

I don’t know what to do.  Everything that I’ve read says that separation anxiety should be over by now, but it is just starting for her.  I’m wondering if it has anything to do with her last tooth coming in.  I also wonder if it has anything to do with the upcoming arrival of her baby brother.

Any advice anyone can offer me would be greatly appreciated.  This very emotional pregnant woman can’t handle hearing her daughter cry like that all the time.