Maybe she needs more sleep! When my daughter was an infant, I couldn't figure out why she was having screaming fits at certain times during the day. Then I came across the book Healthy Sleep Habits, Happy Child, by Dr. Marc Weissbluth. The book helped me come to the conclusion that my daughter was upset because she was tired, and needed a quiet place to sleep. It helped me set up a more appropriate sleep schedule for her, with a nap in the morning, one in the afternoon, and an earlier bedtime. It was amazing how much happier she was with only a few weeks of the new schedule. I now give this book as a gift to everyone who has a new baby, because I found that adequate sleep is very important to having a happy baby (and child).