I have a black astralorp that started laying about a month ago. Her size compared to her friends is a bit smaller. About 2 months ago, she started making coughing or sneezing noises (sounds like a loud 'bok'). Recently, she started swinging her head from side to side and makes weird movements with her head. She started vomiting very little (once a week) about 1 month ago so I didn't pay much attention but today, she vomited a few times. I suspected she had a sour crop since I heard some grumbling sounds coming from her body so I started massaging her crop but sometimes when I do that, she vomits clear slimy liquid. Her poop is normal and there is no lethargy or weight loss. She's also laying normally about 6 eggs a week. This is my first time raising chickens from chicks so I don't have much experience. Any advice or things I can do to help her out?