I've had stomach sensitivity/uncomfort for 6days. having nausea in the morning, and loss of appetite. but no vomitting/diarrhea/fever. wht can it be?

Multiple things: It sounds like you are having morning nausea and stomach discomfort? A common cause of this is gastritis. Have you changed your diet or started any new medication as of late? It is best to see a doctor for a proper history and physical.

Irritation/reflux: You may have a GI problem such as gastritis or dyspepsia. You can try using over the counter medicine like pecidac or zantac (ranitidine) for 1 week; however if not relieved, yuou must be checked.