Do you have crushed oyster shell (calcium) for them to take as they need it? Flock raiser is good but doesn't have enough calcium for layers, and they are at the age where they can start on layer feed. I like Purina or other name brands better than Dumor because they are not as powdery, but I...
Hopefully, she is just getting ready to lay, but I would give her a thorough exam. Feel of her crop for fullness or puffiness, feel for weight loss through the breast bone area after picking her up, check the lower belly for swelling or tightness, look at her droppings for anything unusual, and...