There are a variety of reasons why one may feel sick in their stomach all the time. The sickness can be due to stress. The sickness can be a related to pregnancy. One can also be sick because they have a variety of conditions such as GERD, thyroid disorders, irritable bowel syndrome, or liver disease. One should keep track of all symptoms that they have and discuss these symptoms with their doctor. They should also expect that their doctor may want to run some tests to see what may be causing their symptoms.