Sharp stabbing pain in lower left abdomin. extreme fatigue and generalized pain throughout. constant headache and flu like symptoms?

Infection: I am concerned you may have a kidney infection. You should see a doctor asap before you become more ill. Good luck.

Flu like syndrome: Depending on the duration of your symptoms, would be concerned about a viral process, such as acute mononucleosis. I would consider getting to your doctor or urgent care to get blood work to further define.