My mum had a stress fracture and hobbled miles round London on a weekend away! GP just kept telling her it must be sprained despite not having any trips or falls and kept sending her away with pain killers. After the aforementioned weekend away she finally went to A and E and was diagnosed, it was quite a bad fracture too!
The foot bones are very small , but I have never had a fracture, as far as I know. I hit the top of my instep hard on the corner of my open oven door and it hurt for weeks, went into a black small lump. But repaired itself in a couple of months.