I've been having pain in my left side of my stomach, my appatiate has gotten smaller, & i've been nausea what could this be?

More info: How long have you been feeling this way? Have you had a fever? Have you vomited? Have you had any stool changes? Are you feeling more anxious or stressed out lately? Could be a virus. Could be stress. If this has been going on more than a week or so I would suggest seeing your family doctor to run some tests and have an exam to see if he/she can figure out the cause. Good luck!