This is serious, he might be kidding but it's not funny. If your mom doesn't help, contact NOVA. They are people that help with that kind of stuff. I am truley sorry about what your brother is doing :(
my brother used to beat me up too when i was a kid...he used to squeeze my temples..hurt like heck...but thats what siblings do. he even locked me out of the house and made me pay $5 to get in..(my mom didnt believe me either) so unless you are bleeding or broken bones i think you'll live.