[yorkietalkjilly]

She's either hurting or scared of it(something I know about with a dog like mine who came here with many fears and developed still more along the way which we had to work through one at a time). I would get her thoroughly checked our by your vet for back and joint problems, arthritis, or other medical problems. Even belly problems will make a dog hesitant to climb up steps.

Once the vet has cleared her, then you can come back and we can give you some pointers for how to help her overcome her fear. But a sudden change in behavior, like Lynzy says, has to be checked out as a sign from the dog that there is something amiss medically first and foremost. Changing their behavior by refusing to do something or lying about lethargically or not playing are sometimes the only ways they have of telling us they are having problems. They could yelp out but dogs are stoic and only usually yelp in pain from sudden, shocking or unexpected pain.