No appetite, nausea & severe diarrhea for over a week, now stomach pain right in the center where naval is, and getting chills. should i be concerned?

Gastroenteritis: Sounds like you have gastroenteritis. It is odd that it has been on going for a week though, if you are unable to keep fluids down and maintain hydration, I would recommend following up in the emergency department. Otherwise, drink Gatorade so that you can replenish your electrolytes that are being lost in your diarrhea. Clear liquids and bland diet, follow up with your doctor early this week.

Yes: While without an actual examination, I cannot give specific medical advice on your particular health, worsening symptoms indicating an infection is quite serious and needs prompt medical attention (within hours; less than a day, ER probably the best). might mention that appendicitis would look pretty much right like this........