Although nausea, with meals or without, can often be a manifestation of a non-physical problem, such as stress or emotions, it is often a very common physical problem. Therefore I generally recommend that people who have been having persistent nausea like this for more than a week or two to go see their primary care doctors
to help them figure out if there is something physical going on.
In women, a very common cause of unexpected persistent nausea is pregnancy, so if you are a female (not clear from your question) your doctor will likely ask about when your last period was and will probably perform a pregnancy test.
After ruling that out, common causes of nausea include inflammation of the stomach lining (called gastritis) or a stomach ulcer
. These conditions are worsened by smoking, alcohol, and spicy foods so, while you are waiting to see your doctor, you will want to avoid these.
Numerous other stomach conditions, including constipation and trouble with the gall bladder can also present with nausea. When you go to see your doctor, make sure to mention when the nausea occurs, if it is associated with any particular type of food, and if you have noticed any change in your bowel movements. These observations will help them figure out what is going on.