Answer:
It is most likely that Jerry was experiencing symptoms of a panic attack.
Explanation:
A panic attack can be described as a sudden feeling of fear in an individual due to which several physical reactions are triggered. Panic attacks might be very severe and a person might think that a person is losing his breath and will die or it feels like a heart attack is occurring. A panic attack is not provoked and hence is unpredictable.
As Jerry also feels high sense of nervousness which was not provoked, we can assume that Jack experienced a panic attack.