The Virtual Realities Trilogy

Virtual Realities, Cybersaur, Worldwarp.

Andy Tremain has a terrifying ability. Using virtual reality, he can create monsters from his unconscious mind. And he's obsessed with dinosaurs. A psychiatrist in the United States promises a cure but when Andy and his brother and sister realise they are prisoners rather than guests in Dr Kaplan's luxurious desert complex, Andy's dream becomes a nightmare.
When his powers change and reality itself begins to shift and tear, Andy is so dangerous that society clearly cannot afford to let him live. So the terror continues . . .