Hello Post a detailed clinical examination once can come to an occlusion if they are also staining or proper cavities. Always remember to take caffe of the milk teeth as well, though they would shed in no time and permanent teeth would erupt but they need to be well kept before they shed as they would form the basis for the right occlusion and make sure that the permanent teeth erupted are cavity free.

It might be caries... please consult Dentist and get her teeth cleaned and fillings if possible ...