My dog's back leg constantly shakes?

I have an almost 2 year old Newfoundland dog who's approximately 140 pounds and is healthy and is the perfect weight according to our vet, but his back leg constantly shakes and it has my mom and me worried. We haven't made a vet appointment yet but we are going to after my mom tries her home remedies (she likes homeopathic and naturepathic methods) I was just wondering if anyone knew anything about this..? my mom has just made a doggie-chiropractor appointment because she thinks his hip may be out but, I think it might be something to do more with his nervous system..