Ok, I am trying to figure out what is wrong with my thirteen year old sister. She has no history of any medical problems. She began feeling sick December 26th with severe chills and a fluctuating fever. Throughout the next few days, she would feel okay during the daytime, but get very cold and sick again at night. Now, her eyelids are very swollen all the time and she has no appetite and no energy at all. She has a minor cough, dizziness, and a stuffy nose but she keeps saying that nothing really hurts. We went to the doctor and they did several tests, including strep throat, mononucleosis, bladder infection, flu, and pnuemonia, but they were all negative. The only thing they found was that her white blood cell count was very low. So they sent us home and said they think it is some kind of virus and to see how it does the next few days. Well, she is not getting any better--she just continues to lay down all day and not be able to function. Does anyone have any ideas what this could be?? My mom wants to take her to the hospital.