thorn in side

• nuisanceCause of aggravation
• irritantSource of vexation
• annoyanceState of being bothered
• pestHarmful creature or nag
• botherTo annoy or disturb

aggravation · headache · splinter · prick · needling · constant · nagging · persistent · festering · wound · burden · vexation · irritation · gadfly · bane · torment · affliction · grating