General:
* Distressed
* Upset
* Worried
* Anxious
* Concerned
* Agitated
* Stressed
* Uneasy
* Disquieted
More specific:
* Haunted (for emotional or mental distress)
* Vexed (for annoyance or irritation)
* Harassed (for being persistently troubled)
* Tormented (for intense mental suffering)
* Disaffected (for feeling alienated or disillusioned)
* Oppressed (for feeling weighed down or burdened)
* Plagued (for being constantly troubled by something)
The best synonym depends on the specific situation and the nuance you want to convey.