pebble in the shoe

I put on my socks, yellowish, thin, summery. Then, I covered my left foot by slipping on a shoe, a handsome brown dress shoe, from Famous Footwear. I put on my right shoe. (Truthfully, this sequence may be imposed after the fact. I cannot recall for sure.) Then I felt a pebble in my left shoe. It was an annoyance. It was less than a pebble; call it a pebblette. I removed the shoe and shook it. Nothing seemed to fall out. And I couldn't feel anything with my naked hand as it surveyed the shoe for the culprit. I put the left shoe back on. I walked on it. Pebble (or pebblette) still in the shoe. Problem still afoot, though invisible and not tactile. It has been said such a petty bother can unsettle a person, that it can drive someone (even an abstinent person) to drink. I held that notion in my head to nudge me toward some calmness as expletives prepared to explode into the room peopled only by the author of this blog post. I recalled the broken shoelace and its aftermath chronicled in The Mezzanine by Nicholson Baker. I removed the offending scruple, "again," this time with more comfortable results (as evidenced by a test-walk). 

The metaphorical applications of this vignette await your parsing.

This, from the Online Etymology Dictionary, may help you in your reflections:

scruple (n.)

"moral misgiving, pang of conscience," late 14c., from Old French scrupule (14c.), from Latin scrupulus "uneasiness, anxiety, pricking of conscience," literally "small sharp stone," diminutive of scrupus "sharp stone or pebble," used figuratively by Cicero for a cause of uneasiness or anxiety, probably from the notion of having a pebble in one's shoe. The word in the more literal Latin sense of "small unit of weight or measurement" is attested in English from late 14c.