Well my friend, apparently deduction is lost on you as well. A couple of Steve Smiths quotes.
There is nothing about an ingrown toenail that physically prevents a person from walking besides the pain associated with it. An ingrown toenail does not render a limb unusable, the pain associated with it does.
When Steve Smith states he, and I quote, "couldn't walk anymore," the layperson could generally conclude that pain has reached a point where the individual can no longer tolerate it. Unbearable is a perfectly good synonym to describe this.
But alas, I find no more use beyond this in teaching basic elementary skills to individuals that aren't capable of erudition. Good day.