Overall I m usually in very good health. Three days ago I suddenly felt very weak, no energy, and all my body aches. All joints, legs etc. Ache. Feel listless. Had very slight feeling of high temperature, but thermometer today says normal 98.6. Appetite is diminished, but have no upset stomach. Sinuses are not draining. No sneezing or running nose, or fever. I m trying to take in a lot of liquids; my urine is very cloudy and darker than usual. My age is 81, but I am very fit relatively. I had the customary flu shot last Sept. It s summertime here and we have unseasonable temps of near or above 100 deg. But I have avoided going outside. I live near Portland OR. Do I have simple flu or something more serious? GW