This spider bit one of my children approx 30 minutes ago. He is fifteen years old and came to me and told me he felt a burning sensation on his hand after reaching for the toilet paper whilst on the toilet.Thinking whatever caused it might still be there I walked in to find this spider on floor which I think could be the culprit. Cold anyone help in identifying what it is? We live in Sydney Australia if this helps. Also if anyone could help with solutions to stop the pain that would be greatly appreciated.

Here are two pictures I forgot to attach before sorry,

This looks as if it may be a possibility.
White-tailed spider - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/White-tailed_spider)