My Friend's Cocker Spaniel (about 8 Years Old) Has Been

My friend's cocker spaniel (about 8 years old) has been shaking and restless since this afternoon. He doesn't know what's going on...wondered if his dog may have found some chocolate. Would giving the dog a little hydrogen peroxide help or ??
I think I came to a site for PEOPLE! I was looking for info on dogs. Sorry.