Have you tried ringing Ngala? they will give you help for free over the phone or they do sessions where you can go there (and pay) or you can get someone one on one to come out.

The book Healthy sleep habits, happy child by Marc Weissbluth is a good one!

Sorry i just re read, and you want a specialist as in a doctor? Do you think there is a medical problem? If so Dr Annie O'Donnell at SJofG subi is a Godsend in all things sleep and asthma! Night terrors can be a sign of sleep apnea, or enlarged adenoids. Though they generally only happen within the first couple of hours when they go to sleep, so is waking with night terrors all night?