What qualifications does your equine massage therapist have to diagnose lameness? Not to be harsh, but the education involved to be qualified as one isn't anywhere near veterinary status and does NOT qualify her to diagnose lameness. More massages probably are not the cure. I'm SURE it makes her feel better and it's an awesome thing for you to do for her, but i would get veterinary advice ASAP
Cuehings destroys the metabolism, and laminitis is super common. Especially if it's on and off, I'd make 100% sure she's not laminitic. Even just a little of it has to hurt like heck.
If she's lame I'm sure her shoulder and pec muscles are tight. I have crappy shoulders. When they act up my back muscles get tight from trying to compensate. It's usually the first thing I feel, even before my shoulders freeze up. I don't have a back problem though. My filly has cystic ovary flare ups. Her first cue is that she looks off in the hind end. After I kill the cyst with hormones, I always get her a massage and chiro. After moving off for awhile things get out of whack. She loves it!