Hi! Almost 3 days ago, I began to experience severe nausea, lower back pain, aching legs, chills, and total loss of appetite. Then I began to have frequent sharp pains at the very top of my stomach, right where my ribs meet. I haven't vomited, had diarrhea, or gas. The next day, my lower back pain subsided a little, but lingered around my lower right side. The nausea and sharp pains continued. I had a headache and began to get chills and hot flashes. Days later, I'm still experiencing the sharp pains at the top of my stomach, along with slight nausea.
I believe I had a low grade fever during the onset of my symptoms. (I didn't have a thermometer.)

Does anyone have the slightest inkling as to what is going on with me? Has anyone ever experienced anything like this?

FYI - I'm not pregnant.