Hi ! Good morning. I am Dr Shareef answering your query. If you had some food from outside, food poisoning might be a possiblility. However it should have been associated with loose motions and vomiting as well. Normal ultrasound excludes the possibility of a right sided ectopic as well. If I were your doctor, I would advise you for a urine routine, microscopic, and culture sensitivity test as sometimes a urine infection could also give rise to such symptoms associated possibly with fever.I would also clinically examine your abdomen to rule out the features of acute appendicitis, which is more of a clinical diagnosis than an ultrasound or other supportive investigations including a stool routine test for ova and cyst. In such a situation, I would advise you to wait and watch, and if the pain increases in intensity, to revisit your treating doctor for a review assessment of your abdomen. I hope this information would help you in discussing with your family physician/treating doctor in planning your treatment. Thanks for using the health care magic forum for your query on health. Wishing you an early recovery. Dr Shareef.