Is the gap in the toe-box?
Did you buy shoes with a too-deep toe box (top to bottom) for your foot, yet too narrow (left to right) for your foot?
(You should not be pulling up with the toes in any case. You pull up with the whole leg. If your shins and forefoot are getting too excited about the whole pulling up idea, try consciously relaxing everything from the ankle down and pulling up with everything from the ankle up. See if that makes any difference. And for the moment, I'm ignoring all the studies that say there is no such thing as pulling-up for a mechanical advantage... I'll stay out of that debate entirely.)
"If Americans want to live the American Dream, they should go to Denmark." - Richard Wilkinson