Feel tired/weak after virus infection. cough and snot but no pain. cant shake weakness. antibiotics finish 5 days ago. walking makes dizzy sometimes?

You probably still: have malaise and fatigue from viral infection (?influenza) - weakness may be a lot of dehydration and poor urination. Dizziness may also be a result of dehydration, or just Eustachian tube dysfunction from the viral illness and causing balance problems between your ears. You need rest, fluids, and anti-inflammatory medications to continue for a few more days.