Noun
thorn in the flesh (plural thorns in the flesh)
(idiomatic) A persistent difficulty or something very annoying that will not go away.
He has called upon President Edgar Lungu to dissolve the PF Provincial committee, which he has described as a thorn in the flesh. Source: Internet
North Korea, one of the most isolated countries in the world, is proving to be a thorn in the flesh for the U.S. and some Asian countries, like South Korea and Japan. Source: Internet