Hello, I am so sorry to hear about poor Sally's change in attitude and behavior.
Whenever there is such a huge change in behavior I get very concerned about a medical problem or senility and confusion behind it.
I do believe that she needs an examination and a geriatric blood profile may be helpful in figuring out why she is behaving the way she is. Many laboratories offer a mini panel that hit the highlights and allow you to see if her organs are functioning normally for a reasonable price.
In some dogs as they age their organ systems don't work as well as they once did,
and waste products that their organs usually filter out build up in the blood stream and that affects brain function. They may behave much differently because their brain function isn't normal.
The other possibility given her wandering behavior, barking and confusion which
seemed to worsen at night at her boarding home away from home is that she is experiencing senility, not uncommon at her age. These dogs often forget their housebreaking, seem more confused at night when it is dark, cannot seem to remember whether they have eaten or not, and seem to pace, looking for something they cannot find. They may all of the sudden get into the garbage or chew up things or become aggressive when they never displayed these habits before.
The only way to know for sure what is going on is to check her organ function with
some blood tests.
If her organ function is normal there are medications that can help with senility
and the associated anxiety, such as Anipryl (L-deprenyl or selegiline). There is also a diet formulated for older dogs high in the particular trace minerals and supplements needed for healthy brain function in older dogs called Hills b/d.
I must warn you that these medications and the b/d diet doesn't work for all dogs
and they may not work for long but they may buy her some quality time and help
with her confusion.
Please let me know if you have any further questions.