Mare suddenly kicking out
I have a thoroughbred mare who has uncharacteristically started kicking out with her right hind leg. She does this mostly when ridden, even with children/light riders. I've examined the saddle and tack but can't find anything wrong. Even bareback, and with a different saddle, it's the same. She puts her ears back and doesn't look comfortable. It's always on the left rein, kicking out with the right hind. This has been happening now for about 4 weeks.
In September, she had a white discharge - milky white. I thought she must be in season. Then she started urinating excessively (beginning October). The white discharge appears to have stopped, and the urination is fractionally better. But the kicking is worse.
I have checked her over physically very thoroughly but can't detect what could be wrong. The kicking has damaged the hoof wall of her right hind and I'm worried it will cause other problems like injury to the leg.
If there are any vets out there, or anyone who knows what could be the problem, would be glad for some advice! I have consulted with her vet but not got any satisfactory response.