What Causes Dull Sharp Pain In The Right Abdomen Along With Nausea?

My stomache is somewhat hard at the top above belly button. I feel full all the time. I am nasuated alot but dont throw up and it feels like a hot warm feeling in belly sometimes but rare in chest too. This has been day 5 and I have dull sharp pains starting on right side of abdominal area. Went to er took blood it came back ok and exrays said they think it is gastritis but the pain does not leave and im not eating