influenza
"I began having flu symptoms at work  2 afternoons ago -fever, chills, achiness. I went directly to an urgent care clinic. The flu test was negative, but the physician's assistant said I had come in so quickly that I probably wouldn't test positive yet. Based on my symptoms and the current flu outbreak in our area, she prescribed Tamiflu. 
That night, my fever broke in the middle of the night. When I had the flu before, the fever would return in the evenings, but I've had no more fever and chills. Also no achiness, just fatigue. The only side-effect I experienced from the Tamiflu was moderate diarrhea. 
Much better than being sick for a week or two.l!"