Hi there,
I think that this thread may help you:
one-on-one class help me
Also a great site for ideas for games for little 'uns is:
Genki English, ESL games, songs and ideas to turn ESL lessons into super lessons.
Just get him moving and responding to you first, have a look at the TPR video on Genki English - getting him to 'stand up', 'sit down', 'turn around' etc. Also just play and interact with him in English to get him used to it, then you can introduce flashcards with colours, animals etc and get him to repeat after you. See if he likes colouring/drawing too as that can be fun and relaxing for kids if they're stressed.
Good luck!
Evie