K.W.
Is she cutting her molars? Possibly something in her diet that is giving her gas? My friends daughter was a very difficult child she would throw all out screaming growling tantrums where she was screaming so much that she would make herself throw up and come to find out it was chocolate that was causing this reaction. She completely cut out chocolate and she calmed down, she is 8 now and she still is very strong willed and throws tantrums and growls at her when she is mad but it is much better than it was when she was little. Maybe she is just strong willed or a tad bit jealous of the new baby.