My daughter is 16 months old, and she has 12 teeth now. Up until about a week ago shes always been great about letting me brush her teeth, and she even started doing it herself. But in the past week she has started to refuse to let me brush them. She will clamp her mouth shut, run from me, anything. Its such a fight to get her to brush them. I've bought her cool new toothbrushes, the toddler tooth paste and everything. Any advice?