I have a five and a half month old bottle fed calf that has something wrong with it. She eats grass, but lately, doesn't want to suck the bottle anymore. I have never been able to get her on feed even though she's almost 6 months old. She's losing a little weight and hasn't grown like she should have. Sometimes after she finishes drinking a bottle, she grinds her teeth, but not always. She's not as perky as she used to be either. Any ideas? Thanks.