General antonyms:
* Agitated
* Anxious
* Disturbed
* Excited
* Flustered
* Nervous
* Restless
* Troubled
* Unsettled
More specific antonyms:
* Angry (if referring to emotional calmness)
* Stormy (if referring to weather calmness)
* Turbulent (if referring to a situation's calmness)
* Violent (if referring to physical calmness)
The best antonym will depend on the specific situation and what you want to emphasize.