I have been having very sharp pains in my sternum for five days now. it feels like i am getting poked really hard in the xyphoid process repeatedly?

Costochondritis?: Could be an inflammatory condition of the cartilage there. Doesn't sound specific for a particular diagnosis. May need an exam by a doctor. Your primary care would be a good place to start. OK to try motrin or aleve (naproxen) in the mean time unless you can't take them for some reason - kidney disease in particular. Hope this helps!