Desperate help!

Hello everyone! I am in desperate help. My daughter is almost 7 months old! She is the sweetest baby during the day but she turns in this beautiful-horrible monster after 8:00 pm. She is waking up in the middle of the night to cry for about an hour! I have tried everything! I give her more food before she goes to bed, I have tried to let her cry, I have tried to cuddle with her and nothing seems to work! I am a first time mom so I am not sure how the sleeping habits work on a baby! I am not sure if this is normal or not? Any advice will help. Thanks!