weird dull aches in upper abdomen

Well, i am a 21 year old woman and just this past week experienced very weird symptoms. first it was a dull ache in my upper middle abdomen, where the stomach is. then i lost my appetite completely. eating anything upset my stomach so much, didn't matter what it was. after 4 days of discomfort and 2 trips to the emergency room, the blood tests were normal and they gave me painkillers. they suspect it's my galbladder. however, that means my aches would be on the right side of my body, wouldn't it? the frontal aches have stopped pretty much. my appetite is normal again, but my back is still bothering me, from between my shoulder blades to mid back area and it's constant. very light, but uncomfortable. also the aches switch from left to right side. no aches have ever been horrible. on a scale of 1-10, their only about a 3. just wondering if anyone has experienced symptoms like these and what was the cause? galbladder? stomach?
i'm very concerned and would appreciate some feedback.