It is definitely not saddle fit. She's had time off and even has issues when being lunged or running free in the paddock.
I don't think it is gut issues. I keep her on free choice hay and use hay nets, plus she is on a low grain diet. No signs of abdominal pain/colic.
She is the same in both directions, although maybe a little worse going to the right. The previous vet thought the problem was in both hinds which is why he injected her stifles. She is willing to go forward, but sometimes I feel like she is trying to run away from the discomfort.
I know this isn't an attitude issue, as she is so willing to do anything else. She has never given me an attitude about anything during her training career. If I ask her to fix her lead she even tries to fix it, but can't hold it more than 2 strides. As for fitness, she does have muscle loss on her topline. I've tried ground driving her and working on cavalettis and did try hill work before her last vet appointment but it really hasn't seemed to make any difference.