Horse hind end lameless?

I have a 6 year old mare, appendix (mostly tb). I bought her 3 months ago. She is showing signs of lameness in her hind end. She is somewhat sickle hocked. When walking a circle, her outside hind twists. The hoof twists in, and the hock bows outwards. Walking a straight line is better but the hocks still wobble outwards. She is shod in all 4, I dont believe it is the trim and the heels are even. Her stride is short, she isn't tracking up, doesn't want to canter. Always switching weight from right to left hind. Won't stand square. What could this be? I have an equine chiropractor coming but not for another 2 weeks. Any suggestions? I've researched everything inside and out but can't find anything that seems to fit.