This very affable dancer came in to see if there was anything I could do to help a feeling of pulling and spasm in the sole of his foot and in his calf. He wondered if orthotics might help in his dance shoes. As we were discussing his history, I found out that his foot problems started about ten years prior, when he was dancing in ballet shoes which irritated the sole of his foot so much where their seam was that a small internal scar was created on the nerve to his big toe. His MRI showed this scar tissue, and nothing else of note. Since then, if he were to do a few full relevés (tip-toe moves) he'd get extreme shooting pain into his toes. So he had to avoid full relevés.
Kudos to him, as full relevés are the staple of what a top-level dancer does. So he had to fake it both artistically and athletically. When I carefully palpated the ball of his foot, I was able to feel this mass in his foot. It was between the bones at the ball of his foot and the skin, and felt like a little electric cord under a rug.
I then asked him to push down with his big toe very strongly into the resistance of my hand. This caused the spasm and pull discomfort to surface, the complaint he'd been experiencing most recently. I then asked him to walk. On the uninvolved foot, he walked in the normal heel to toe push-off way. On the involved side, he didn't push off. He pulled up. He was walking on the good side, and doing a subtle prance-march on the painful side, to avoid pushing his weight into the scar at the ball.
I then looked at his back alignment, and asked him some questions. As I suspected when I examined him, his orthopedist and physical therapist were treating him for a sacroiliac problem. Over the years, the sacroiliac joint on the same side as the bad foot had rotated more and more out of position. It is the marching muscle, called the psoas, which rotates the sacroiliac joint out of position when it gets too tight, His psoas was always tight, and neither he nor his physical therapist would ever have any success in trying to loosen it.
I created a little pad to explicitly off-load the scar from ground contact while in a relevé or while in a walking push-off position. First time he was able to relevé in ten years without pain. I made him orthotics to do the same in his street shoes, and showed him how to do these pads in his dancing shoes. He returned in five weeks, all pains gone (including back and hip pain), moving to Las Vegas to get married!