ODD is oppositional defiant disorder, and it's certainly a tough one to deal with. Here's a link explaining it.
http://www.emedicine.com/PED/topic2791.htm
KS, I cannot say anything about weigted blankets, but, here's a link on how to make one. It shouldn't be too expensive, in case it doesn't work...
http://www.ont-autism.uoguelph.ca/blanket.html
I wish you luck. And btw, welcome to SR!
Shalom!