Sibling Rivalry Draws Swords

We recently had a baby. Great News!
During the first week, our daughter, our youngest, stayed home from school sick with a fever. She enjoyed being around the baby, touching him, kissing him, smiling at him and even singing to him. Yet people kept asking, "How is your daughter taking to the baby and not being the youngest anymore."

'Just great,' I said often. It was the truth, and the transition to bringing a baby into our family and now having four kids seemed to be going smoothly. My daughter got well and went back to school, who had written off her absence due to the birth of her baby brother.

Throwing Up
Then a few weeks later, she came into our baby early in the morning. I was so tired from having gotten up every two hours for feeding that I didn't even notice her, until I rolled over in the morning and saw her lying there. I fell back asleep. In my dream I was startled awake by the sound of retching.

I turned over and opened my eyes to find my daughter, coughing and ready to throw up. She turned over and vomited a bit on the blankets and sheets, and I grabbed her and took her to the bathroom to finish.

My wife and I cleaned up, and were left scratching our heads wondering about this out of the ordinary event with our daughter.

What's that Smell?
One night I went in to check on my daughter. Her room was filled with a revolting smell. I told my wife. "Oh she probably just farted."
Then a short while later, my daughter, S. got up and came into our room. She complained that she thought she dirtied her pants. My wife checked and she found that S. had pooped in her pants at night, really bad.

Release the Wrath
A week later, we let S. stay home from school, after she claimed to have a sore throat. After the boys get off school and she is the only one at one besides the baby, she wanted to play and watch shows on the computer. This was unacceptable. Either she was sick and needed to be bedridden or she should be in school.
She tore into a tantrum, getting angry and yelling "All you do is take care of the baby. You don't care about me. I just want to kill that baby!"
We kept her home from school and made sure to give her lots of attention.
Later in the day she turned to us and said, "I'm sorry. I just wanted to be with you." She gave the baby a kiss.