Hello,
My guess is "arthritis" symptoms.
Ask your vet about getting her "complete" workup. If it is arthritis, you might consider mentioning her trying a Cartrophen program.
This involves getting injections of Cartrophen into the areas that present the most pain in her legs, etc,.
These are done every week for 3 - 4 weeks to enhance effectiveness and promote relief of pain. (then 1 every 3 motns following initial course) Prices range between: $15 to $30 per visit.
Axercise is vital, but don't overdo it until she starts walking better. Base the distance on the pain level she is displaying.Talk to the vet about proper dosages of Glucosamine and Chondroitin for her breed in particular, and see. You should use both ingredients for best results.
Also, you could get her a soft bed, preferably flat one, about 2 to 3 inches thick to assist in comfort at this very painful time. Some of these pads have warmers built in to add warmth to the joints, thus relieving some pain as well. These are just some things for you to consider,and to discuss with your vet. Also, ask if a change in diet would be of benefit.
I hope this has helped you some. Feel free to write again if anything further is needed. Take care, and I hope she is feeling better soon!
God Bless.