thorn in (one's) flesh
A person or thing that is frequently problematic, aggravating, or annoying. My new neighbors blast music at all hours of the day and night—they're a real thorn in my flesh. My car has become such a thorn in my flesh—today is the third day this week that it wouldn't start for me!
thorn in one's flesh
Also, thorn in one's side. A constant source of irritation, as in Paul's complaining and whining are a thorn in my flesh, or Mother's always comparing us children-it's a thorn in our sides. This metaphoric expression appears twice in the Bible. In Judges 2:3 it is enemies that "shall be as thorns in your sides"; in II Corinthians 12:7 Paul says his infirmities are "given to me a thorn in the flesh."