[targonrotts]

before anything, i would get her to a vet(asap) and get xrays of her hips/back and knees area.
rule out hip displacia, back injury,arthritis,or cruciate.
anything could have happened.for some of these problems, the earlier attended to, the better.
if she did a bad move, it's cold, or heavy exercised, she could have aggrevated something.
rule out what is wrong first and take it from there.
there are meds for most conditions and things to help her be more comfortable.
welcome to the forums...keep us posted on your girl's results.