The Man in the Habit of Hitting Me on the Head with an Umbrella

Every day in Petar's life is worse than the previous one, which means that every new day is the worst day in his life, until... one day a mysterious, mute stranger starts hitting Petar at his head with an umbrella. He hits without an intention to stop. Whatever Petar does to liberate himself from this menace, the strange little man is constantly by his side.