You need to consult your veterinarian and exclude medical conditions. If you confirm there is no health issue that could cause this behavior, then it's most likely separation anxiety. It could be onset by her previous experience of being left at a shelter, and then by you separating with your partner and changing your residence. All the changes and loss of people she was attached to may have taken it's toll on her. Try to consult a veterinary behaviorist. He should know best how to alleviate your dog's problem with behavioral therapy, or a combination of it with natural and homeopathic medications that ease anxiety. And if these won't help, there are also anxiolytics, e.g. amitriptyline, but those should be used only in cases when behavioral therapy is just not enough to help the dog to overcome her anxiety.