Elderly dog had bad experiences recently/not wanting to go out.

well as you all know Polly has had one thing after another recentlly, she consumed a lot of chocolate and suffered poisoning from this, she has her weak heart, and due to the stroke she had a few years back she has slight brain damamage, ever so slight but its there. Then there was when she got attacked by our neighbours staffie, and well she has had it rough.
Well she has started being less inclined to well go out, i have to tempt out for walkies, as soon as we get out into the fields and the leads go off she just stays close to me. I really think its taken it toll on her, someone has to sit out in the garden with her when she goes for a pee if you dont she will howl the house down and dig awahy at the glass in the door to get in we took her to the vets for her check up...last week and mentioned this to him and he said it could be post traumatic stress syndrome, he said it is known in dogs. So i was wondering what you all thought to this, the vets diagnosis i mean?
also is there anything i can do, to well get her over this hurdle?

oh dear luke,you and polly have had a rough time have you tried rescue remedy?it is probably the cheapest thing to start with.you can get it from boots and superdrug or any health food shop.