63 yr old female. Last night I thought I was getting the flu; body aches, shivering chills, headache, cough, severe joint pain, hurt all over. Went to bed and shivered under the blankets. I expected 2-3 days of symptoms to recover. Woke up shortly after sweating, very hot, throwing off the blankets. Then slept soundly all night. Woke this morning and I feel perfectly healthy. No pain or discomfort at all. My concern is that this is the third time this has happened in the past six weeks. What s happening to cause such severe symptoms that disappear so quickly?