It may be related to losing Plummer, or at least that's where it might have started. Molly reacted very strongly to losing Fletcher this summer. They weren't that close, or at least I never noticed, but after he died, she started acting very different, acting afraid of her food, very nervous in general. She is normally a very laid back, reserved dog. She had just turned 11 a few months earlier when this started. Definitely get him checked for pain, but keep this in mind as well.