There is an old Chinese proverb; “Failure results not from the length of the journey or the height of the mountain but the pebble in one’s shoe.”
We have all had it at some point – the pebble that is.

We are running or walking or hiking and feel a small irritant. We think to ourselves that maybe our sock bunched up. But, after a bit, we realize its something else. So we move our foot around a bit or kick it up against a rock or log, or maybe sideways on the ground. The hope is that that kick will move the irritating thing to the side where we won’t feel it.
Sometimes it works for a while. But it always comes back. We are always better off to stop, take off your shoes, and clear whatever the problem is. Even the smallest pebble can cause problems. It can start with a hot spot and develop into a blister. It can cause a hole to develop in the sock. It can tear into the insole’s covering.
So stop and remove it.
Several weeks ago I was at the Gold Rush Adventure Race and encountered a similar situation. One of the racers came into the transition area and in the process of changing socks, I told her I’d clean out her shoes. The race route had taken runners through muddy areas and some had gone down into her shoes.
As I used my hands to clean inside her shoes, I found very rough hard edges under both heels. I thought it was a defect or tear in the insole. Surprisingly, it was hardened mud that was so hard, it took a lot of pressure to remove it from the insole. This must have hurt through the socks – but the racer had not bothered to clear out her shoes.
In reality, it might be a pebble – or mud. In either case, you are always better off to take a moment and get rid of the irritant.