I'm not sure but maybe the sounds made by the dolphins had a special effect on Nikki. It also can be a child desperate need of communication because he really wanted to stay in the tank with the dolphins. We'll never know.
I've heard about dolphins therapy with children with mental diseases and I suppose it works because the therapies are still running.
£10,500 is a lot of money. I'm sure it was difficult to raise all the money but being also a mother I know you do anything for your children.