14 years is old for a dog. I had a husky that lived til she was 15. She had the same problem, I kept her out of pain best I could, but eventually, time caught up with her and her old body just wouldn't do what she wanted, I took her to the vet and had to put her down as she was suffering. Talk to your vet as they can help to keep your dog out of pain.
My dog is 14yrs old now and her back legs are weak. It seems like sometimes she is drunk... when she stands still her back legs will go one way, while her bottom half of her body leans towards the opposite side. What could be wrong?
As most dogs get older they have a tendency to get arthritis in their backs. Making it hard and painful for them to control their back leg functions. Your dog is 14 and it will only get worse, I'm sorry to say. But your Vet does have some medications to help with pain and make life a little easier for her. Please call your Vet as soon as you can.
She could be suffering with diabetes too, that might be where her weakness is coming from.
And check for hip dysplasia.