My Three Yr. Old Granddaughter Cries Her Teeth Hurt Her.

My three yr. old granddaughter cries her teeth hurt her. Now it hurts in front. We don't know if it is actually her teeth or because she was at the dentist and he said it was, her molars trying to come in. Times she screams and holds her head, many times a day. This has been going on for about 6 months. If it is her molars, shouldn't they have come in by now?