You can ask a shoe repair shop to stretch the medial side of the toe box. They've got cool stretcher thingys. Or you can stretch it yourself with a broom handle.

Jam the broom handle into the area that touches your big toe.
Work the broom handle into the shoe in that spot, stretching it, for about one or two TV shows. (you need something to distract you, cuz this is a boring procedure)

Keep trying the shoe to make sure you are beating up the upper in the right spot.

Repeat as necessary.