Hi I Been Feeling Nauseas For A While Now I

hi i been feeling nauseas for a while now i believe its been almost three weeks. And it hasn't gone away and i've hurt my knee and i've been feeling it pulse and it hurts if i'm resting it. i've also been get headches and sometimes chills, and i can't really walk to well on that leg. Also, a i think i sprained my ankle again on the same leg what should i do.