A feeling of being sick in the stomach can describe the symptom of nausea, which may lead to vomiting, notes MedicineNet. When this symptom occurs frequently, there can be many causes for it, such as stomach irritation, GERD, hepatitis, pancreatitis, brain tumor, food allergies and medications. Treating nausea first requires diagnosing the specific cause.
Some other causes for feeling sick in the stomach can be linked to issues with organs, including the gallbladder and esophagus. Other factors that can lead to nausea and vomiting are anxiety and stress, according to WebMD. This is because emotional states can cause a physical reaction in the body, such as in the digestive system.