I Have This Nauseous Feeling Through Out The Day, For

I have this nauseous feeling through out the day, for the last 3 days. Also have this very tender feeling in my abdomen. Had my normal motions (i.e. once a day in the morning), but it was very loose. I ran a temperature too. Checked with my family physician and was told that this could be due to some food intake that has upset my stomach. After taking the medicines last night....I woke up this morning with the same nausea feeling and terrible bitterness in the mouth. I have not vomited though.

Could you help me out.....and let me know what you think would be the cause of this horrible feeling?