If your teenage daughter complains of painful periods, try this before going to a specialist.
On the day before her flow and cramping starts, there is usually some bloating or gas. You have a chance here to help her. Have her tell you when this occurs and give her Aleve twice daily or Motrin/Advil three times daily for the next two days. This will make it harder for prostaglandins to be made in her body. Prostaglandins play a big part in her cramping and decreasing them should make her cramping better. The most important part here is to start the medicine BEFORE the actually cramping starts. If you wait until she is cramping, she may not receive much relief.
If you try this and she is still in pain, she should see the gynecologist to rule out any medical conditions that can be treated.