what causes bloating in the stomach, the feeling of being full, easily becoming nausea and nervous in the stomach.
Not too sure what you mean by being nervous in the stomach but will assume that you feel a sinking sensation sometimes described as “butterflies in the stomach”. Many of the symptoms you describe can be attributed to indigestion for which there may be no actual cause and occurs every now and then for no reason. It tends to arise after overeating, eating too fast, certain spicy foods and alcohol consumption.
However there are several conditions that may cause these symptoms, like gastritis, peptic ulcers (stomach or duodenum), hiatal hernia, acid reflux, gallbladder and even pancreas conditions. You can find a list of causes in the articles below. Identifying foods or situations that tend to precipitate these symptoms may assist with narrowing down the cause. You should speak to your doctor who can assess you further and conduct other tests and investigations to identify the cause.