A sudden feeling of nervousness in the stomach may be due to bloating and cramping caused by improper diet, catching a cold, or discomfort caused by gastric neurosis. 1. Flatulence and cramps: Catching a cold in the abdomen, consuming cold drinks with gas in them, or eating cold food can lead to flatulence and stomach cramps, resulting in discomfort such as a sudden feeling of tension in the stomach. 2. Gastric neurosis: It is mostly seen in non-organic lesions caused by psychological, physiological, social and other factors, with discomfort such as epigastric discomfort, nausea, and a feeling of tension in the stomach. If the symptoms of the sudden onset of nervousness in the stomach are not relieved, or accompanied by other symptoms, you should go to the hospital in time to consult a doctor to identify the cause and then give targeted treatment.