nervousness

strain, stress, tension

alarm (also alarum), anguish, consternation, desperateness, desperation, discomfort, discomposure, dismay, distraction, distress, disturbance, edginess, hand-wringing, jitters, jumpiness, panic, tremor

angst, fearfulness, torment, upset, vexation

cold feet, doubt, dread, foreboding, incertitude, misgiving, presentiment, suspense, uncertainty

compunction, qualm, scruple