Hello!
Jackson had something similar happen in January. He came out limping and I had NO idea why. He's a pretty active dog, but at the time, it was winter and he hadn't been for a few days. It seemed to come out of nowhere.
Vet took x-rays, nothing, checked for LP, nothing, hips, nothing. So she tested him for Lymes disease... came out positive! Lymes affects joints, etc. So she put him on a 30 day antibiotic and gave him pain meds for 7 days, problem solved.
Here was my thread,
http://www.yorkietalk.com/forums/yor...some-help.html