My mare Cocoa did the exact same thing to me.....After some closer checking, it was the saddle that was pinching in on her withers. So I got another saddle and that helped...then I found that she had weak hocks. So the farrier had to do some corrective shoeing and she was a whole lot better. I felt so bad thinking about how many times I would circle her and all until she settled, when the whole time it was the saddle. That meant she would give in to me and just work through the pain.

Check saddle fit, etc. Try a double pad to see if she reacts any different.