I too have a stress fracture in my right foot (3rd and 5th metasarsal) that happened 6 months ago. It has never shown up on xray, but an MRI found the fracture. I have been fitted for a custom insert, and it seemed to be improving, but anytime I move my foot quickly, it's like it gets strained, and I have a lot of pain again. I'm at my wit's end. I have been to endochronologist who has found no underlying causes. I'm looking for any kind of ideas!