What happened to bud when he feels like someone stuck a red hot nail into his left cheek in bud not buddy?

In "Bud, Not Buddy," when Bud feels like someone has stuck a red hot nail into his left cheek, it signifies the intense pain and emotional turmoil he is experiencing. This moment reflects his feelings of rejection and vulnerability, highlighting the harsh realities of his life as an orphan. The physical pain symbolizes the deeper emotional scars he carries from his past, particularly his struggles with abandonment and his quest for belonging.