I never had that but apparently it's associated with anxiety..

Anxiety

An anxiety disorder differs from normal stress and anxiety. It is more severe and long-lasting, and interferes with work and relationships. Anxiety disorders include Generalized Anxiety Disorder, Panic Disorder, Social Phobia, Post-Traumatic Stress Disorder, and Obsessive/Compulsive Disorder.
Symptoms:

• Physical – Heart palpitations, chest pain, rapid heartbeat, flushing, hyperventilation, shortness of breath, dizziness, headache, sweating, tingling and numbness, choking, dry mouth, nausea, vomiting, diarrhea, muscle aches, restlessness, tremors/shaking
• Psychological – Unrealistic and/or excessive fear and worry, mind racing or going blank, decrease concentration and memory, indecisiveness, irritability, impatience, anger, confusion, restlessness or feeling “on edge” or nervousness, tiredness, sleep disturbance, vivid dreams
• Behavioral – Avoidance of situations, obsessive or compulsive behavior, distress in social situations, phobic behavior

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Community Psychiatric Clinic - Information and Resources - Signs and Symptoms of Mental Illness