Need help, 2 year old

My daughter just turned two last month. Lately her behavior is insane, totally out of control. From the second she wakes until we go to sleep. Constant bad mood. Always fighting. Hitting. Doesn’t listen. I have no clue what I did wrong..but clearly something. She wakes up in a bad mood and I can’t figure out how to help her. I’m trying different activities, going outside more, helping with the baby. ( I also have a 6 month old.) need some help. What do I do?