It happens, that shoes that fit perfectly in the shop magically shrink on the way home and does not fit so good anymore. They are too tight in this place and too small in another. It happens and nothing can change it. Not to ditch such a capricious pair (which the only a couple of hours earlier seemed to be a perfect match) I use one trick that breaks them in and makes them perfect again.
While stretching too tight shoes you have to be prepared for a few minutes of pinched toes. Put the shoes on and blow warm air from a hair dryer onto tight areas, while flexing and stretching the feet. For maximum benefit, wear a pair of thick socks.