there is a support group for parents called 'lyme aid parents' see the following link;-
Good luck
http://health.groups.yahoo.com/group/Lyme_Aid_Parents/
Greetings --
I see you don't have a response to your post yet -- I don't know of a website focussing on children with Lyme, but it sounds like a very good idea -- kids being out playing are maybe even more at risk of Lyme than those of us who are inside all day pounding a keyboard (like me).
There have been some posts here about people with children, but no mention of a support group for kids. You might try googling/searching for "kids lyme" or something like that --
Let us know if you find one, and of course come back and visit us here when you can.
Best wishes to you and yours --