I had an endurance saddle that broke and I didn't know it (It had reactor pannels.)
It took me a month before I did anything but hand walked my horse. Then I spent another month with a chiropractor who worked every two weeks on Vashka's back. Then I rode Vashka bareback, but only at a walk and a trot. THEN, three months later, I rode him. Only he still had vulnerable spots. So we went back to handwalking. Now we're back to riding in a saddle that fits. I know -- because I check his back every time I get off his back.