My lurcher, Charna, lost her best buddy, Mr Bean, and became extremely nervous, making large detours rather than passing other dogs. When I got my greyhound, Kim, however, she immediately re-found her confidence and marched up to other dogs happily to say hello. Maybe she just needs a new hero in her life? I know it's a big step.
I had a similar situation a few years ago when I lost my girl. My boy didn't cope very well at all and only regained his confidence when I adopted another female greyhound. Sometimes they just need a buddy.