It’s chronic and exaggerated worry and tension, even though nothing seems to provoke it.
[psychcentral.com]
For this disorder to be diagnosed, several other symptoms (such as a tendency to tire easily, difficulty concentrating, and muscle tension) must accompany the anxiety.
[msdmanuals.com]
Their worries are accompanied by physical symptoms, especially trembling, twitching, muscle tension, headaches, irritability, sweating, or hot flashes.
[psychcentral.com]