I am sorry that you have been waiting for a response. I recently just logged onto the site and noted that your question hasn't yet been answered. I am a licensed veterinarian with over 25 years’ experience and would be happy to work with you if you are still needing assistance.
Of course it is impossible to know without the benefit of a physical exam, but my first thought would be possible pain due to degenerative joint disease (DJD) or arthritis. This can make a dog restless and can causes changes in breathing. Most often, in larger breed dogs, the hips or the hindlegs are affected but pain can occur anywhere for any reason. There would be no harm in using a glucosamine type product for her available at the pet store, but I would stay away from over the counter pain medications as many are not safe or effective and without a diagnosis, you could be doing her more harm than good.
Another possibility could be the start of a behavioral condition that we see as dogs age called cognitive dysfunction. It is similar to dementia in humans but in early stages, the dogs may only exhibit signs of restlessness.
As you can see, there there are very many other reasons for this change in behavior and even after an exam it is not always clear. It would be helpful to your veterinarian if you were to keep a log of any changes in her behavior that you are already noting or that you may see occur until you can have her evaluated by your vet.
I hope this is helpful. Please let me know if you have ANY other questions. My goal is to give you 100% satisfaction and if you are not yet satisfied, please reply so I can clarify for you.
My posted replies are for general education only and not meant as a diagnosis. Only after a thorough veterinary examination can a diagnosis for your pet be made and specific treatments be advised or medications be prescribed.